Heterojunction fabrication and noble metal deposition serving as efficacious means for promoting photocatalytic activity attract huge interests. Here, a series of ternary Ag/AgBr/BiOIO3 composite photocatalysts that integrate the above two aspects are prepared by in situ crystallization of Ag/AgBr on BiOIO3. The photocatalytic performance is first investigated by degrading MO with visible light and UV light irradiation. The results indicate that Ag/AgBr/BiOIO3 composites present strengthened photocatalytic activity compared with BiOIO3 and Ag/AgBr under both light sources. Distinct activity enhancement levels corresponding to different mechanisms with UV and visible light illumination are uncovered, which are closely related to the applied light source. The universal catalytic activity of Ag/AgBr/BiOIO3 is surveyed by decomposition of diverse antibiotics and phenols, including tetracycline hydrochloride, chlortetracycline hydrochloride, bisphenol A, phenol, and 2,4-dichlorophenol which discloses that this ternary heterojunction photocatalyst demonstrates unselective catalytic activity with universality. Importantly, Ag/AgBr/BiOIO3 displays a strong mineralization ability, completely decomposing BPA into CO2 and H2O. This work affords a new reference for designing heterojunction photocatalyst with multiple advantageous effect and powerful capability for environmental purification.Keywords: AgBr; Antibiotics; BiOIO3; Phenols; Photocatalysis; SPR;
Monolayered photocatalytic materials have attracted huge research interests in terms of their large specific surface area and ample active sites. Sillén-structured layered BiOX (X = Cl, Br, I) casts great prospects owing to their strong photo-oxidation ability and high stability. Fabrication of monolayered BiOX by a facile, low-cost, and scalable approach is highly challenging and anticipated. Herein, we describe the large-scale preparation of monolayered BiOBr nanosheets with a thickness of ∼0.85 nm via a readily achievable liquid-phase exfoliation strategy with assistance of formamide at ambient conditions. The as-obtained monolayered BiOBr nanosheets are allowed diverse superiorities, such as enhanced specific surface area, promoted band structure, and strengthened charge separation. Profiting from these benefits, the advanced BiOBr monolayers not only show excellent adsorption and photodegradation performance for treating contaminants, but also demonstrate a greatly promoted photocatalytic activity for CO2 reduction into CO and CH4. Additionally, monolayered BiOI nanosheets have also been obtained by the same synthetic approach. Our work offers a mild and general approach for preparation of monolayered BiOX, and may have huge potential to be extended to the synthesis of other single-layer two-dimensional materials.Keywords: BiOBr; CO2 reduction; Liquid-phase exfoliation; Monolayered nanosheets; Photodegradation;
Macromolecules November 14, 2017 Volume 50(Issue 21) pp:8317-8317
Publication Date(Web):October 19, 2017
DOI:10.1021/acs.macromol.7b01741
A series of photomechanical fibers was fabricated with a thermal drawing method by using liquid-crystalline random copolymers containing azobenzene and biphenyl groups in side chain. After being post-cross-linked under mild conditions, these fibers showed photoinduced bending motion away from the light source even though homogeneous alignment of mesogens was observed along the drawing direction. This abnormal photoinduced deformation of the obtained fibers is far different from previously reported light-directed motions about liquid-crystalline fiber and film materials. The interesting photomechanical deformation can be ascribed to the surface volume expansion caused by photoisomerization of azobenzene moieties. Then the photoinduced bending behaviors of these fibers containing different azobenzene concentrations and cross-linking densities were systematically investigated, suggesting that the location of photoresponsive azobenzene played an important role in deciding their photomechanical behaviors. This provides one convenient way of controlling over the photoinduced bending direction through the location of light-active moieties in side chain or cross-linker. In addition, irradiation of visible light accelerated the recovery of bent fibers. These fibers possess quick response, large deformation, and good thermal stability, indicating their promising applications for smart devices and energy conversion devices.
Co-reporter:Xuelian Yu, Ruifeng Du, Baoying Li, Lei Liu, and Yihe Zhang
The Journal of Physical Chemistry C March 30, 2017 Volume 121(Issue 12) pp:6712-6712
Publication Date(Web):February 28, 2017
DOI:10.1021/acs.jpcc.6b12868
Cu2ZnSnS4 (CZTS) and AuAg alloy are important functional materials that have received considerable research interest. In this work, we develop a solution based synthetic method to combine these two materials into CZTS–AuAg heterodimers at low temperature. These CZTS–AuAg heterodimers demonstrate prominent catalytic activities toward oxygen reduction reaction (ORR) in alkaline medium, and they show a 20-fold increase in mass activity compared to the single component of AuAg nanocrystals. Meanwhile, compared to the CZTS–Au heterostructures, the addition of Ag has remarkably increased the four-electron selectivity of the catalysts. X-ray photoelectron spectroscopy (XPS) analysis reveals that the promising properties are mainly attributed to the electronic coupling between the semiconductor and the noble metal domain in the heterostructure and the alloying effect of Au–Ag. This work proves that it is possible to maximize the catalytic activity through not only the alloying method but also its interaction with a semiconductor using a metal alloy–semiconductor heterostructure.
The Journal of Physical Chemistry C July 24, 2014 Volume 118(Issue 29) pp:15640-15648
Publication Date(Web):July 1, 2014
DOI:10.1021/jp500645p
Different samples of gadolinium (Gd)-doped Bi2WO6 were obtained by hydrothermal means, and their photocatalytic activities for degradation of rhodamine B (RhB) under visible-light irradiation were researched. The successful incorporation of Gd3+ ions into Bi2WO6 was detected by XRD and XPS, and the prepared samples have also been characteriazed by SEM, TEM, HRTEM, DRS, and PL. The results suggested that Gd doping has great influences on the visible-light photocatalytic activity as well as the microstructure. Appropriate doping content greatly improve photocatalytic activity due to the electron shallow-trapping mechanism for the efficient separation of electron and hole pairs, and the 1% Gd–Bi2WO6 sample with flower-like structure exhibited the highest photocatalytic activity. It has already been confirmed by photocurrent generation and electrochemical impedance spectra. The present research provides a simple and valid method for improving the visible-light-responding photocatalytic activity and fabricating hierarchical architectures of Bi2WO6.
Waste and Biomass Valorization 2017 Volume 8( Issue 1) pp:203-207
Publication Date(Web):2017 January
DOI:10.1007/s12649-016-9617-y
Flue gas desulfurization (FGD) gypsum and textile fibers constitute two large-scale industrial wastes generated in China. In this work, these wastes were used for making foamed concrete which can increase the energy efficiency of buildings. The effects of the W/S ratio, super plasticizer amount, foaming agent as well as textile fibers contents on the compressive strength and density values of the porous FGD gypsum plaster materials was systematically investigated. The highest compressive strength value of the gypsum blocks was 1.6 MPa after 7 days of curing, and the measured density value was 617 kg/m3. The obtained results suggest an effective way to recycle FGD gypsum and textile fiber wastes in order to produce not only low-cost and effective buildings materials, but also to lessen the environmental impact.
•A series of 3D hierarchical bismuth oxyiodides were fabricated.•These bismuth oxyiodides include BiOI, Bi4O5I2, Bi4O5I2-Bi5O7I junction and Bi5O7I.•They exhibit different microstructures and photoactivity against diverse pollutants.•Charge separation efficiency is mainly responsible for their photocatalytic activity.Design of three-dimensional (3D) hierarchical architectures and nano-phase-junctions are of huge significance for semiconductor photocatalysis. Herein, we report the fabrication of a series of 3D hierarchical bismuth oxyiodides via in situ phase transformation and phase-junction construction utilizing BiOI microspheres as self-sacrificed template through a facile calcination strategy. The multiform bismuth oxyiodides obtained at different temperatures include hierarchical BiOI, Bi4O5I2, Bi4O5I2-Bi5O7I phase-junction and Bi5O7I. These bismuth oxyiodides exhibit very distinct microstructure and band structure, and their photoabsorption was orderly tuned from 700 to 400 nm, rendering the adjustable oxidation and reduction ability of band energy levels. The photocatalytic activity of the bismuth oxyiodide series is systematically assessed by degradation of diverse antibiotic and contaminants, such as tetracycline hydrochloride, bisphenol A (BPA) and azo dye Rhodamine B (RhB). It disclosed that they present discrepant photocatalytic performance with activity order of Bi4O5I2-Bi5O7I > Bi4O5I2 > Bi5O7I > BiOI, which is closely associated with the charge separation efficiency, band structure and surface area. Additionally, the photocatalytic mechanism and degradation pathway are also surveyed. The study may furnish new insights into development of novel 3D hierarchical architectures and nano-phase-junctions for heterogeneous photocatalysis.Download high-res image (219KB)Download full-size image
•Polyurethane foam (PUF) based bismuth oxyhalides photocatalysts are synthesized.•BiOX/PUF shows enhanced photodegradation activity for dye, phenol and antibiotic.•BiOX/PUF foams also show improved photocatalytic H2 evolution rate.•BiOX/PUF foams display easy recovery, good recycling and excellent controllability.Photocatalysis currently remains a series of key challenges, such as difficult recovery of powder, low efficiency, etc, which grievously impede the practical application of powdery photocatalysts in environmental remediation and renewable energy generation. In this work, we integrate a flexible and porous organic matrix polyurethane foam (PUF) with nanosheet-array-like bismuth oxyhalides (BiOX) as efficient and stable photocatalysts via a facile dipping-hydrolysis means. The BiOX/PUF foam photocatalysts uncover profoundly promoted photocatalytic performance for treating multiform organic contaminants ranging from azo dye, phenol to antibiotic, in comparison with the powdery counterparts. These foam photocatalysts also display enhanced photocatalytic activity toward water splitting into H2 evolution. Significantly, they show absorbing performance in many aspects, including high stability, easy recovery, good recycling and excellent controllability and adaptability, strongly boding for their promising practical prospect. The study may not only advance a series of practical photocatalysts for environmental control and renewable energy generation, but also have the potential to be extended to development of other high-performance photocatalytic materials.Download high-res image (183KB)Download full-size image
•Single-unit-cell layer established 3D Bi2WO6 by SDBS-assisted assembled strategy.•It shows a strong selectivity for adsorption on positively-charged organic dyes.•It presents highly enhanced photocatalytic activity for degradation and H2 evolution.•Systematic photoelectrochemical experiments confirm the promoted charge separation.•Single-unit-cell 3D Bi2WO6 is a promising dye-sensitized photoanode for ORR.Single-layer catalysis sparks huge interests and gains widespread attention owing to its high activity. Simultaneously, three-dimensional (3D) hierarchical structure can afford large surface area and abundant reactive sites, contributing to high efficiency. Herein, we report an absorbing single-unit-cell layer established Bi2WO6 3D hierarchical architecture fabricated by a sodium dodecyl benzene sulfonate (SDBS)-assisted assembled strategy. The DBS− long chains can adsorb on the (Bi2O2)2+ layers and hence impede stacking of the layers, resulting in the single-unit-cell layer. We also uncovered that SDS with a shorter chain is less effective than SDBS. Due to the sufficient exposure of surface O atoms, single-unit-cell layer 3D Bi2WO6 shows strong selectivity for adsorption on multiform organic dyes with different charges. Remarkably, the single-unit-cell layer 3D Bi2WO6 casts profoundly enhanced photodegradation activity and especially a superior photocatalytic H2 evolution rate, which is 14-fold increase in contrast to the bulk Bi2WO6. Systematic photoelectrochemical characterizations disclose that the substantially elevated carrier density and charge separation efficiency take responsibility for the strengthened photocatalytic performance. Additionally, the possibility of single-unit-cell layer 3D Bi2WO6 as dye-sensitized solar cells (DSSC) has also been attempted and it was manifested to be a promising dye-sensitized photoanode for oxygen evolution reaction (ORR). Our work not only furnish an insight into designing single-layer assembled 3D hierarchical architecture, but also offer a multi-functional material for environmental and energy applications.Download high-res image (194KB)Download full-size image
•Bi4Ti3O12 was synthesized by a one-pot hydrothermal process and sol-gel method.•Diverse morphologies are obtained by manipulating the mineralizer concentration.•Bi4Ti3O12 shows universal photoreactivity for removing contaminants and antibiotics.•It shows ultrasonic-assisted piezoelectric-catalysis for MO degradation.•Superoxide and hydroxyl radicals take effects in the piezoelectric-catalytic process.Development of multi-responsive catalytic materials is a highly meaningful and challenging subject for forwarding the understanding on catalysis mechanism. In this work, we for the first time disclose the piezoelectric-catalytic performance and morphology-dependent photocatalytic activity of Bi4Ti3O12. Via introducing and manipulating the mineralizer sodium hydroxide, we developed a series of Bi4Ti3O12 catalysts with diverse morphologies, including nanorods, slice-assembled microspheres, nest-like hollow microspheres, and cube assembly. The photocatalytic activity of these hydrothermally-yielded Bi4Ti3O12 as well as sol-gel derived Bi4Ti3O12 is investigated by degradation of phenol, and the photocatalytic mechanism is explored. The Bi4Ti3O12 microsphere exhibits the most efficient degradation activity, and also presents universal photoreactivity for removing multiform contaminants and antibiotics, like bisphenol A, rhodamine B, chlorotetracycline and tetracycline hydrochloride, boding for its promising practical applications. Significantly, Bi4Ti3O12 demonstrates a high piezoelectric-catalytic performance for ultrasonic-assisted decomposition of methyl orange, bisphenol A and tetracycline hydrochloride. It is uncovered that both powerful superoxide (O2−) and hydroxyl (OH) radicals are generated with production rates of 6.4 and 2.4 μmol g−1 h−1, respectively, which take crucial roles in the piezoelectric-catalytic process. The corresponding mechanism is tentatively speculated. This work may push forward to the development of multi-responsive catalytic materials, and provide insights into piezoelectric-catalysis for environmental applications.Download high-res image (174KB)Download full-size image
•BiOCl/Bi12O17Cl2 phasesjunctions are obtained by an one-pot hydrothermal process.•BiOCl/Bi12O17Cl2 shows higher degradation activity than BiOCl and Bi12O17Cl2.•It shows an universal photocatalytic activity for diverse contaminants degradation.•Enhanced charge separation is responsible for the enhanced degradation activity.Fabrication of homo/hetero-junctions by coupling of wide-band gap semiconductor and narrow-band gap semiconductor is desirable as they can achieve a decent balance between photoabsorption and photo-redox ability. Herein, a n-n type bismuth oxychloride homogeneous phasejunction BiOCl/Bi12O17Cl2 was developed by facilely manipulating the basicity in a one-pot hydrothermal process. Compared with BiOCl which only responds to UV light, the photo-responsive range is remarkably extended to visible region. The BiOCl/Bi12O17Cl2 phasejunctions show much higher photocatalytic activity than the single BiOCl and Bi12O17Cl2 toward degradation of methyl orange (MO) under simulated solar light. In particular, it presented a high photo-oxidation ability in degrading diverse industrial contaminants including 2,4-dichlorophenol (2,4-DCP), phenol, bisphenol A (BPA) and tetracycline hydrochloride. Based on a series of photoelectrochemical and photoluminescence measurements, the fortified photocatalytic performance of BiOCl/Bi12O17Cl2 phasejunctions was manifested to be attributed to the efficient separation and transfer efficiencies of photoinduced electron-hole pairs because of the junctional interface formed between BiOCl and Bi12O17Cl2. The study may not only furnish a high-effective photocatalyst in the application of environment purification, but also pave a path to fabricate agnate phase-junctional photocatalyst.BiOCl/Bi12O17Cl2 phasejunctions show much higher photodegradation activity than the single BiOCl and Bi12O17Cl2 and universal photocatalytic activity for treating diverse c ontaminants.Download high-res image (129KB)Download full-size image
Chinese Chemical Letters 2017 Volume 28, Issue 12(Volume 28, Issue 12) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.cclet.2017.09.017
Heterostructure photocatalyst fabrication is of great significance for promoting the photoreactivity and solar-energy utilization efficiencies. In this work, AgI/BiOIO3 heterostructure photocatalysts are synthesized by a facile in-situ crystallization of AgI on BiOIO3. The photocatalytic performance is first surveyed by decomposition of model dye methyl orange (MO) separately with illumination of UV light and visible-light (λ > 420 nm). It indicates that AgI/BiOIO3 shows highly improved photocatalytic activity regardless of the light source, which should be attributed to the matchable band energy levels between AgI and BiOIO3, benefiting the efficient charge separation. Notably, AgI/BiOIO3 shows a universal photocatalytic activity for treating diverse antibiotics and phenols, including tetracycline hydrochloride, chlortetracycline hydrochloride, 2,4-dichlorophenol (2,4-DCP), phenol and bisphenol A (BPA), and the strong mineralization ability of AgI/BiOIO3 was also demonstrated. Additionally, the different mechanisms under UV and visible light irradiation are investigated in detail. This work provides a new reference for design and manipulation of high-performance nonselective heterostructure photocatalyst for environmental purification.Download high-res image (232KB)Download full-size imageAgI/BiOIO3 heterostructure shows enhanced UV and visible-lightphotocatalytic activity enhancement, and can decompose many antibiotics and industrial contaminants with high mineralizationability.
Co-reporter:Hongwei Huang, Hongling Ou, Jingwen Feng, Xin Du, Yihe Zhang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017 Volume 518(Volume 518) pp:
Publication Date(Web):5 April 2017
DOI:10.1016/j.colsurfa.2017.01.045
•Iodine doped BiOIO3 was synthesized by a facile hydrothermal process.•Photo-responsive range of BiOIO3 is extended from UV to visible light.•Iodine doped BiOIO3 shows much higher photocatalytic activity than BiOIO3.•Superoxide radicals and hydroxyl radicals are generated under visible light.Visible-light active photocatalytic performance of a layered bismuth-based photocatalyst BiOIO3 was achieved by iodine ion doping through a facile hydrothermal process. Compared to pure BiOIO3, the light responsive range of BiOIO3 is drastically extended from UV to visible light, and the adjustable band gap is also achieved. The photocatalytic experiments revealed that I-doped BiOIO3 displays significantly enhanced photocatalytic activity (over 6-fold increase) toward degradation of two types of azo dyes methyl orange (MO) and Rhodamine B (RhB) with visible light illumination (λ > 420 nm). The photoelectrochemical measurement also confirms the greatly promoted photo-activity of modified BiOIO3. The band structure evolution and visible-light induced photocatalytic mechanism are investigated in detail. It is demonstrated that the visible-light response of I-doped BiOIO3 mainly originates from a larger down-shift of the conduction band than valence band. Additionally, two powerful radicals superoxide radicals (O2−) and hydroxyl radicals (OH) are produced in the photodegradation process, which are responsible for the high visible-light photocatalytic activity.I-doped BiOIO3 displays significantly enhanced photocatalytic activity (over 6-fold increase) toward degradation of methyl orange (MO) and Rhodamine B (RhB) with visible light illumination (λ > 420 nm).Download high-res image (201KB)Download full-size image
•Cl intercalated g-C3N4 is obtained via pyrolysis of melamine and excessive NH4Cl.•Cl intercalation endows g-C3N4 with multiple superiorities.•It shows significantly enhanced photoreduction and photooxidation performance.•The Cl intercalation advantages are confirmed by experiments and DFT calculations.Metal-free graphitic carbon nitride (g-C3N4) shows tremendous potentials in energy and environmental domains. Nonetheless, amelioration on the crystal configuration, electronic structure and microstructure of g-C3N4 for high-performing visible-light photocatalysis is still challenging and anticipated. Here we report the development of chlorine (Cl) intercalated g-C3N4 via co-pyrolysis of melamine and excessive ammonium chloride (excessive is very pivotal). This protocol renders not only Cl intercalation in the interlayer of g-C3N4, but also a homogeneous porous structure, thereby endowing g-C3N4 with multiple superiority effects, including significantly promoted charge migration by establishing interlayer pathway, up-shifted conduction-band level, narrowed band gap as well as enhanced surface area. The as-prepared Cl intercalated mesoporous g-C3N4 parades outstanding photocatalytic performance for water splitting into H2, CO2 reduction, liquid and air contaminants removal. The most enhanced photocatalytic performance was obtained at Cl-C3N4-3 for H2 evolution activity, which shows a 19.2-fold increase in contrast to pristine g-C3N4, accompanying with a high apparent quantum efficiency of 11.9% at 420 ± 15 nm. Experimental and DFT calculations results co-disclose that the aforementioned advantageous factors account for the profoundly boosted photooxidation and photoreduction capabilities of g-C3N4 under visible light. The present work may furnish a bottom-up tactic for integrally advancing g-C3N4, and also hold huge promise to be extended to other layered materials for photochemical or photoelectrochemical applications.Download high-res image (140KB)Download full-size image
AbstractElectrochemically up-regulated surface-enhanced Raman spectroscopy (E-SERS) effectively increases Raman signal intensities. However, the instrumental requirements and the conventional measurement conditions in an electrolyte cell have hampered its application in fast and on-site detection. To circumvent the inconveniences of E-SERS, we propose a self-energizing substrate that provides electrical potential by converting film deformation from a finger press into stored electrical energy. The substrate combines an energy conversion film and a SERS-active Ag nanowire layer. A composite film prepared from a piezoelectric polymer matrix and surface-engineered rGO that simultaneously presents high permittivity and low dielectric loss is the key component herein. Using our substrate, increased E-SERS signals up to 10 times from a variety of molecules were obtained in the open air. Various tests on real-life sample surfaces demonstrated the potentials of the substrate in fast on-site detection.
Raman-Signalverstärkung per Fingerdruck wurde durch Kombination eines flexiblen, piezoelektrischen und dielektrischen Energieumwandel- und Speicherfilms mit Silbernanodrahtschichten erhalten. In der Zuschrift auf S. 2693 ff. beschreiben Y. Zhang, Q. An et al. ein selbstanregendes SERS-Trägermaterial (SERS=oberflächenverstärkte Raman-Streuung), das Filmdeformationen in gespeicherte elektrische Energie umwandeln kann, die dann Elektronen in eine Silbernanodrahtschicht injiziert und die darin gemessenen SERS-Signale erhöht.
AbstractEfficient photo- and piezoelectric-induced molecular oxygen activation are both achieved by macroscopic polarization enhancement on a noncentrosymmetric piezoelectric semiconductor BiOIO3. The replacement of V5+ ions for I5+ in IO3 polyhedra gives rise to strengthened macroscopic polarization of BiOIO3, which facilitates the charge separation in the photocatalytic and piezoelectric catalytic process, and renders largely promoted photo- and piezoelectric induced reactive oxygen species (ROS) evolution, such as superoxide radicals (.O2−) and hydroxyl radicals (.OH). This work advances piezoelectricity as a new route to efficient ROS generation, and also discloses macroscopic polarization engineering on improvement of multi-responsive catalysis.
Co-reporter:Dr. Hongwei Huang;Shuchen Tu;Chao Zeng; Tierui Zhang; Ali H. Reshak; Yihe Zhang
Angewandte Chemie International Edition 2017 Volume 56(Issue 39) pp:11860-11864
Publication Date(Web):2017/09/18
DOI:10.1002/anie.201706549
AbstractEfficient photo- and piezoelectric-induced molecular oxygen activation are both achieved by macroscopic polarization enhancement on a noncentrosymmetric piezoelectric semiconductor BiOIO3. The replacement of V5+ ions for I5+ in IO3 polyhedra gives rise to strengthened macroscopic polarization of BiOIO3, which facilitates the charge separation in the photocatalytic and piezoelectric catalytic process, and renders largely promoted photo- and piezoelectric induced reactive oxygen species (ROS) evolution, such as superoxide radicals (.O2−) and hydroxyl radicals (.OH). This work advances piezoelectricity as a new route to efficient ROS generation, and also discloses macroscopic polarization engineering on improvement of multi-responsive catalysis.
In this study, highly monodispersed Cu2SnZnS4 NCs with a quasi-spherical structure were prepared to construct a sandwich-type electrochemical immunosensor for alpha-fetoprotein detection. Quaternary Cu2SnZnS4 NCs as novel biomimetic catalysts show an efficient intrinsic peroxidase-like activity for H2O2 reduction. This excellent catalytic activity is ascribed to the higher electroconductivity than those of the binary Cu2S and ternary Cu2SnS3 NCs. Moreover, β-cyclodextrin-functionalized graphene sheets are used as substrate materials that can capture large amounts of primary antibodies due to host–guest interaction and high surface area. Under the optimized conditions, the electrochemical immunosensor exhibites a wide working range from 0.5 pg mL−1 to 10 ng mL−1 and a detection limit of 0.16 pg mL−1 at a signal-to-noise ratio of 3. Good sensitivity, reproducibility, and stability demonstrate its potential application in clinical diagnostics.
Here, we report a facile method to fabricate NiCo2O4 nanoneedles on mesocarbon microbeads (MCMB) and form a unique urchin-like core–shell structure. In this composite, the MCMB not only provided high conductivity to benefit effective electron transfer, but also offered abundant adsorption points to load the NiCo2O4 nanoneedles. The aggregation of the NiCo2O4 nanoneedles was therefore alleviated and each NiCo2O4 grain was unfolded to gain easy access to the electrolyte for efficient ion transfer. When the NiCo2O4@MCMB composite was evaluated as an electrode material for supercapacitors, a synergistic effect was exerted with high specific capacitance (458 F g−1 at 1 A g−1) and large reversibility (116% capacitance retention after 3000 cycles), both of which were of great advantage over individual MCMB and NiCo2O4 nanoneedles. The NiCo2O4@MCMB was also used to construct a symmetric supercapacitor, which showed enlarged voltage profiles and could light the LED device for a few minutes, further confirming its excellent electrochemical performance.
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 17) pp:9008-9013
Publication Date(Web):2017/08/21
DOI:10.1039/C7NJ02253K
In this work, a sandwich-type electrochemical immunosensor was fabricated for the detection of carcino embryonic antigen (CEA) with the novel label of quaternary chalcogenide nanocrystals – Cu2ZnSnS4. They illustrated efficient intrinsic peroxidase-like activity in the catalytic reduction of peroxide hydrogen, which was ascribed to the synergistic effect of elemental composition in quaternary chalcogenides. Meanwhile, because of a high specific surface and good biocompatibility, three-dimensional Au nanoparticle loaded graphene aerogels were selected as substrates to capture more antibodies (Ab1). Under optimal conditions, the immunosensor exhibited a wide linear range from 0.5 pg mL−1 to 20 ng mL−1 with a low detection limit of 0.15 pg mL−1 (S/N = 3) for CEA detection. In addition, high sensitivity, excellent selectivity, good reproducibility and stability were obtained for the immunosensor. All of these results show that the novel immunosensor has a promising application for the quantitative detection of CEA in clinical diagnosis.
A facile solution-based method was developed to combine the advantage of amorphous nanoscale red P sheets and highly conductive graphene, forming a high-performance P/graphene composite anode for advanced lithium ion batteries. Graphene can be easily expanded into a 3D framework in solution with rich interior porosity and abundant adsorption points, which enables a large percentage of red P to be loaded and form a uniform P/graphene hybrid structure. The nanoscale and amorphous features of red P effectively reduce the volume expansion and mechanical stress within individual P sheets, thereby alleviating P pulverization during cycling. The well dispersed graphene serves as a buffer layer to accommodate the volume expansion and adsorb the stress during electrochemical reactions, thereby maintaining a robust electrode structure. Besides, the highly conductive graphene greatly enhances the ionic/electronic conductivity of the electrode, which favors efficient redox reactions and high P utilization. Based on the superior composite structure, the potentials of both components can be fully exerted, resulting in excellent electrochemical performance. The P/graphene electrode delivered a high reversible capacity of 1286 mA h g−1 based on the weight of the composite after 100 cycles at 200 mA g−1. Even at a high current density of 1000 mA g−1, the composite electrode exhibits a high capacity of 1125 mA h g−1, revealing its potential as a high-performance P-carbon composite anode for advanced lithium ion batteries.
Co-reporter:Hongwei Huang;Ke Xiao;Na Tian;Fan Dong;Tierui Zhang;Xin Du
Journal of Materials Chemistry A 2017 vol. 5(Issue 33) pp:17452-17463
Publication Date(Web):2017/08/22
DOI:10.1039/C7TA04639A
Metal-free graphitic carbon nitride (g-C3N4) has sparked considerable interest due to its efficient photocatalytic activity in many fields. Development of new tactics toward improving the photocatalytic performance of g-C3N4 remains active and challenging. In this study, we uncover an unprecedented template-free precursor (melamine) pre-treatment protocol to achieve porous g-C3N4 nanosheets for efficient photocatalytic reduction and oxidation reaction. The introduction of thiourea solution in the hydrothermal pre-treatment process etches the surface of melamine, thus yielding the porous, thin g-C3N4 nanosheets. The microstructure and porosity of g-C3N4 can be adjusted only by controlling the thiourea amount. The as-obtained porous g-C3N4 nanosheets are found to be endowed with not only increased specific surface area, but also enhanced photoabsorption in the visible light region. Systematic characterizations of the charge movement behavior (transient photocurrent, linear sweep voltammetry, electrochemical impedance spectra, photoluminescence and surface photovoltage spectroscopy) disclose that the separation of photogenerated charge carriers is remarkably boosted by fabricating such a porous nanosheet structure. Benefiting from these advantages, porous g-C3N4 nanosheets present profoundly enhanced visible-light photocatalytic performance for H2 evolution (3.3-fold increase) and NO removal from the gaseous phase (5.5 times increase) in contrast to the pristine bulk g-C3N4. Our current study may offer an alternative approach to designing high-performance g-C3N4 nanomaterials for energy and environmental applications.
Composites Part A: Applied Science and Manufacturing 2017 Volume 99(Volume 99) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.compositesa.2017.03.029
High-dielectric-constant (high-k) polymer nanocomposites are demonstrated to show great promise microelectronics industry. In this work, sandwich-like SiO2 encapsulated graphene oxide hybrids (SiO2@GO) were fabricated throng a sol–gel method to enhance the dielectric properties of PI. Series of analysis, such as X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that SiO2 were successfully grafted onto the surface of GO and formed a sandwich-like core–shell structure hybrids. Then, polyimide (PI) composites filled with SiO2@GO were prepared via in-situ polymerization method. A dielectric constant of 73 (40 Hz) was obtained for SiO2@GO/PI composites as the fraction of SiO2@GO was 20 wt%. In order to improve the dielectric properties of composite, two kinds of coupling agents, 3-aminopropyl triethoxysilane (APTS) and 3-glycidoxypropyltrimethoxysilane (GPTS), were used to modify the surface of SiO2@GO. GPTS-SiO2@GO/PI composite had an increased dielectric constant of 79 and a decreased loss of 0.25 at 40 Hz. The significantly enhanced dielectric performance of GPTS-SiO2@GO/PI composite was caused by the good dispersion of GPTS-SiO2. In addition, the different dielectric performance of composites modified by different coupling agent was also discussed. This work could help researchers further understand the mechanism of fillers’ interface on the dielectric properties of composites.Download high-res image (148KB)Download full-size image
Co-reporter:Hongwei Huang, Chao Zeng, Ke Xiao, Yihe Zhang
Journal of Colloid and Interface Science 2017 Volume 504(Volume 504) pp:
Publication Date(Web):15 October 2017
DOI:10.1016/j.jcis.2017.05.048
We herein describe the coupling of solid-solution and heterojunction in a 2D-1D BiOCl0.5I0.5/Bi5O7I hierarchical architecture for optimizing photoabsorption, energy band levels and charge separation, thereby promoting the photo-oxidation and molecular oxygen activation performance. BiOCl0.5I0.5/Bi5O7I shows a core-shell-like structure with BiOCl0.5I0.5 thin nanoflakes (∼3 to 8 layers) homogeneously vertical coating on the surface of Bi5O7I strips. The photo-responsive range of BiOCl0.5I0.5/Bi5O7I can be orderly tuned from 450 nm to 650 nm by increasing the BiOCl0.5I0.5 content. Regardless of visible light (λ > 420 nm) or UV light (365 nm) irradiation, BiOCl0.5I0.5/Bi5O7I casts highly promoted photocatalytic activity in decomposing methyl orange (MO) compared to the BiOCl0.5I0.5 and Bi5O7I. This enhancement on full-spectrum photoreactivity is attributable to the facilitated charge separation derived from BiOCl0.5I0.5/Bi5O7I heterojunction with intimate interfacial interaction, which is approved by transient photocurrent response under visible and UV–vis light. To probe the photocatalytic mechanism, active species trapping tests are performed over BiOCl0.5I0.5, Bi5O7I and BiOCl0.5I0.5/Bi5O7I, which reveal superoxide radical (O2-) and hole (h+) take dominant roles in photo-oxidation reaction. BiOCl0.5I0.5/Bi5O7I was also found possessing a stronger ability in molecular oxygen activation with a O2- production rate of 2.22 × 10−7 mol L−1 h−1, which far outperforms Bi5O7I (1.35 × 10−7 mol L−1 h−1) and BiOCl0.5I0.5 (1.54 × 10−7 mol L−1 h−1). It further corroborates the efficient band charge transfer between BiOCl0.5I0.5 and Bi5O7I. This work may furnish a new concept on smart design of high-performance photocatalytic materials via manipulating multiple strategies.Download high-res image (199KB)Download full-size image
Journal of Colloid and Interface Science 2017 Volume 508(Volume 508) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.jcis.2017.08.042
A central issue in understanding photo-redox catalysis is the facet-dependent charge movement behaviors that include bulk charge separation, surface charge transfer and interfacial charge migration. To get in-depth insight into these complicated processes steered by different exposing facets, herein BiOCl with exposed (0 0 1) and (0 1 0) facets engaged as the model are investigated. The BiOCl-(0 1 0) and BiOCl-(0 0 1) single-crystalline sheets are separately synthesized via hydrothermal and hydrolysis routes. In contrast to BiOCl-(0 1 0), BiOCl-(0 0 1) demonstrates highly promoted photo-redox performance for H2 generation and degradation of pollutants. The facet-dependent charge movement behaviors were surveyed by surface photovoltage spectroscopy (SPV), transient photocurrent, linear sweep voltammetry, continuous wavelength photocurrent, and electrochemical impedance spectrum (EIS). All the photoelectrochemical and photoelectric measurement results reflect that BiOCl-(0 0 1) exhibits superior charge separation and migration efficiencies in the whole charge movement process than the BiOCl-(0 1 0). Besides, a higher charge carrier density (3.1-fold enhancement) was also observed for BiOCl-(0 0 1) compared to BiOCl-(0 1 0). Our current work is expected to further our understanding on facet-dependent charge movement behaviors and offer new insight into design of high-performance photocatalytic/photoelectrochemical materials.Download high-res image (133KB)Download full-size image
Co-reporter:Na Tian, Yihe Zhang, Xiaowei Li, Ke Xiao, Xin Du, Fan Dong, Geoffrey I.N. Waterhouse, Tierui Zhang, Hongwei Huang
Nano Energy 2017 Volume 38(Volume 38) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.nanoen.2017.05.038
•A precursor-recrystallization strategy was first employed to obtain advanced g-C3N4.•It shows 3D mesoporous structure established by ultrathin N self-doped nanosheets.•It shows enhancement on surface area, photoabsorption and charge separation.•A superior photocatalytic H2 evolution rate of 3579 μmol h−1 g−1 was achieved.•The apparent quantum efficiency is as high as 27.8% at 420 nm.Graphitic carbon nitride (g-C3N4) has attracted enormous research attention as a promising low cost, visible-light driven semiconductor photocatalyst. However, low photoabsorption efficiencies and unsatisfactory charge separation limit the potential of g-C3N4 in many applications, motivating attempts to manipulate the structure and electronic properties of g-C3N4 to achieve improved performance. Here we describe a novel precursor-reforming strategy that ultimately affords 3D mesoporous ultrathin g-C3N4 with superior photocatalytic performance compared to conventional calcination-derived g-C3N4. We demonstrate that during hydrothermal treatment of melamine and urea, melamine undergoes an irreversible monoclinic to orthorhombic phase transformation, and the additive urea (excess typically 3-fold) serves as an additional N source and porogen. Calcination of the orthorhombic melamine yields mesoporous g-C3N4 with enhanced photoabsorption properties and an outstanding photoactivity. A 23-fold increased hydrogen evolution rate of 3579 μmol h−1 g−1 (λ > 420 nm) was achieved with an apparent quantum efficiency (AQE) of 27.8% at 420 ± 15 nm, a level of performance far beyond any AQE previously reported for ultrathin/porous/doped g-C3N4 photocatalyst. Our work conclusively demonstrates a new synthetic strategy towards high performance g-C3N4-based photocatalytic materials for energy applications.An unprecedented precursor phase-transformation and recrystallization protocol was reported for the first time to yield mesoporous g-C3N4 with an outstanding photoactivity. A 23-fold increased hydrogen evolution rate of 3579 μmol h−1 g−1 (λ > 420 nm) was achieved with an apparent quantum efficiency (AQE) of 27.8% at 420 ± 15 nm.Download high-res image (228KB)Download full-size image
Co-reporter:Chengyin Liu, Hongwei Huang, Liqun Ye, Shixin Yu, Na Tian, Xin Du, Tierui Zhang, Yihe Zhang
Nano Energy 2017 Volume 41(Volume 41) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.nanoen.2017.10.031
•Horn-like hollow mesoporous ultrathin g-C3N4 tube was first developed.•It shows an efficient spatial anisotropic charge separation between tube shells.•Greatly boosted carrier density and surface charge transfer efficiency are achieved.•A superior photocatalytic H2 evolution rate of 1353.6 μmol h−1 g−1 was obtained.•The apparent quantum efficiency is as high as 14.3% at 420 nm.Metal-free graphitic carbon nitride (g-C3N4) has triggered huge interests for converting solar energy into fuels. However, direct-calcination derived bulk g-C3N4 always suffers from low surface area and high recombination of charge carriers, prompting attempts to foster g-C3N4 nano/microstructures to achieve high performance. Conventional routes, like templating method, always yields g-C3N4 with tedious morphology and requires post-treatment. Here we release the first report on development of horn-like hollow mesoporous ultrathin (HHMU) g-C3N4 tubes via first forming a horn-like Br-containing intermediate followed by further decomposition transformation under co-pyrolysis of melamine and substantial NH4Br. The multiple-superiorities achieved here (hollow/mesoporous/ultrathin/horn-like) allows g-C3N4 high surface area, drastically boosted bulk charge separation, carrier density and surface charge transfer efficiency. This advanced g-C3N4 thus casts outstanding photocatalytic performance for H2 evolution with an apparent quantum efficiency (AQE) of 14.3% at 420 ± 15 nm, far exceeding most of reported g-C3N4. HHMU g-C3N4 also delivers a strengthened photocatalytic CO2 reduction activity into CO and CH4. Selective photo-deposition results provide an in-depth insight into charge movement behavior and high photo-reactivity that the photo-generated electrons migrate to the outer shell and holes prefer to transfer onto the inner shell of HHMU g-C3N4 tubes, thus achieving efficient spatial anisotropic charge separation. The current study may furnish a reference towards developing efficient tactics for integrally advancing g-C3N4 for renewable energy generation, and disclose a new perspective into promoting charge separation via microstructure design.Horn-like hollow mesoporous ultrathin g-C3N4 tubes are developed via an intermediate-mediated strategy, which are allowed high surface area and efficient spatial anisotropic charge separation between outer and inner shells of g-C3N4 tubes, thus demonstrating outstanding photocatalytic H2 evolution with an AQE of 14.3% at 420 ± 15 nm and efficient CO2 reduction activity.Download high-res image (301KB)Download full-size image
Co-reporter:Xiangming Li, Yingmo Hu, Qi An, Xinglong Luan, Qian Zhang and Yihe Zhang
Nanoscale 2016 vol. 8(Issue 17) pp:9376-9381
Publication Date(Web):08 Apr 2016
DOI:10.1039/C6NR02022D
Multifunctional plasmonic particles serving simultaneously as catalysts and label-free reporting agents are highly pursued due to their great potential in enhancing reaction operational efficiencies. Copper is an abundant and economic resource, and it possesses practical applicability in industries, but no dual-functional copper-based catalytic and self-reporting particles have been reported so far. This study proposes a facile strategy to prepare high-performance dual-functional copper-based composite particles that catalyze reactions and simultaneously serve as a SERS (surface enhanced Raman spectra) active, label-free reporting agent. Polyelectrolyte-modified reduced graphene oxide particles are used as the reactive precursors in the fabrication method. Upon adding Cu(NO3)2 solutions into the precursor dispersions, composite particles comprised by copper/copper oxide core and polyelectrolyte–graphene shell were facilely obtained under sonication. The as-prepared composite particles efficiently catalyzed the conversion of 4-nitrophenol to 4-aminophenol and simultaneously acted as the SERS-active substrate to give enhanced Raman spectra of the produced 4-aminophenol. Taking advantage of the assembling capabilities of polyelectrolyte shells, the composite particles could be further assembled onto a planar substrate to catalyze organic reactions, facilitating their application in various conditions. We expect this report to promote the fabrication and application of copper-based multifunctional particles.
Co-reporter:Deyang Zhang, Yihe Zhang, Xiaowei Li, Yongsong Luo, Hongwei Huang, Jiaping wang and Paul K. Chu
Journal of Materials Chemistry A 2016 vol. 4(Issue 2) pp:568-577
Publication Date(Web):25 Nov 2015
DOI:10.1039/C5TA07105D
Ternary spinel metal oxide ZnCo2O4 with Co2+ at the tetrahedral sites (8a) in the spinel Co3O4 replaced by Zn2+ is promising in energy storage and an economical way to fabricate low-toxicity nanostructured ZnCo2O4 is described. Theoretical calculation confirms the rationality of the experimental scheme and elucidates the underlying reason for the increased band gap. The high electrochemical activity and excellent stability of the ZnCo2O4 NFs//ZnCo2O4 NW symmetrical device suggest large potential for energy storage applications. The fabricated device boasts a capacity of 220.6 F g−1 at a current density of 2 A g−1 and long-term cycling stability with 67.5% of the capacitance retained after 8000 cycles. The maximum energy density of 60.04 W h kg−1 at a power density of 1.4 kW kg−1 and a power density of 7 kW kg−1 at an energy density of 23.72 W h kg−1 are achieved at an operating voltage of 1.4 V. This combined experimental and theoretical study provides insights into the design and controllable preparation of nanomaterials for energy storage applications.
Effective and robust interfacial protein retention lies at the heart of the fabrication of protein-based functional interfaces, which is potentially applicable in catalysis, medical therapy, antifouling, and smart devices, but remains challenging due to the sensitive nature of proteins. This study reports a general protein retention strategy to spatial-temporally confine various types of proteins at interfacial regions. The proteins were preserved in mesoporous silica nanoparticles embedded in covalently woven multilayers. It is worth noting that the protein retention strategy effectively preserves the catalytic capabilities of the proteins, and the multilayer structure is robust enough to withstand the bubbling catalytic reactions and could be repeatedly used due to conservation of proteins. The spatiotemporal retention of proteins could be adjusted by varying the number of capping layers. Furthermore, we demonstrate that the protein-loaded interfacial layers could not only be used to construct catalytic-active interfaces, but also be integrated as the power-generating unit to propel a macroscopic floating device.
Co-reporter:Tao Huang, Qi An, Xinglong Luan, Qian Zhang and Yihe Zhang
Nanoscale 2016 vol. 8(Issue 4) pp:2003-2010
Publication Date(Web):15 Dec 2015
DOI:10.1039/C5NR08129G
A variety of small molecules with diameters around 1 nm possess a range of functions, such as antibiotic, antimicrobic, anticoagulant, pesticidal and chemotherapy effects, making these molecules especially useful in various applications ranging from medical treatment to environmental microbiological control. However, the long-term steady delivery (release or permeation) of these small molecules with adjustable and controllable speeds has remained an especially challenging task. In this study, we prepared covalently cross-linked free-standing few-layered GO films using a layer-by-layer technique in combination with photochemical cross-linkages, and achieved a controlled release of positively charged, negatively charged, and zwitterionic small molecules with adjustable and controllable speeds. The steady delivery of the small molecule lasted up to 9 days. Other functionalities, such as graphene-enhanced Raman spectra and electrochemical properties that could also be integrated or employed in delivery systems, were also studied for our films. We expect the special molecular delivery properties of our films to lead to new possibilities in drug/fertilizer delivery and environmental microbiological control applications.
Co-reporter:Hongwei Huang, Ke Xiao, Shixin Yu, Fan Dong, Tierui Zhang and Yihe Zhang
Chemical Communications 2016 vol. 52(Issue 2) pp:354-357
Publication Date(Web):22 Oct 2015
DOI:10.1039/C5CC08239K
We herein report a facile and general approach to modulating the band energy level of semiconductors for visible-light photocatalysis via iodide surface decoration. This strategy enables the wide-band-gap Bi2O2CO3 to possess a continuously tunable band gap and profoundly boosted visible-light photocatalytic performance for dye degradation and NO removal.
The homogeneous BiOBr/Bi heterojunctions photocatalyst was synthesized from {001} facet dominated BiOBr flakes via a PVP-assisted in situ reduction reaction at room temperature. The high {001} facet exposure of BiOBr could induce the homogeneous distribution of metallic Bi on the surface of BiOBr. The introduction of PVP not only effectively protected the uniform structure but also largely promoted the photocatalysis properties. Compared to the bare BiOBr, an obviously enhanced photochemical performance was achieved over the homogeneous BiOBr/Bi pertaining to methyl orange (MO) degradation and photocurrent generation. The highly enhanced photocatalytic activity can be attributed not only to the surface plasmon resonance effect and efficient separation of electron–hole pairs by the metallic Bi but also to its uniform and regular structure. The present work provided a new approach to the development of attractive bismuth-based-photocatalysts/metallic Bi heterostructures with controllable structures and photocatalytic performance.Keywords: BiOBr; In situ reduction; Metallic Bi; Photocatalyst; Plasmon resonance effect; PVP-assisted;
We for the first time disclose the integrated effects of a semiconductor p–n heterojunction and dominantly exposed reactive facets that are enabled in a facile way. Unlike most of the reported semiconductor heterojunctions that are constructed by compositing the individual components, in this work, we report the composition–transformation fabricating BiOI/BiOIO3 heterostructure via an in situ reduction route by using thiourea as the reducing agent. This reducing process enables BiOIO3 dominant exposure of the {010} reactive facet, and the exposed percentage can be effectively tuned by monocontrolling the thiourea concentration. The photocatalysis and photoelectrochemical properties of samples are assessed by surveying the decomposition of methyl blue (MB) and photocurrent generation under simulated solar light or visible light illumination. The heterostructured BiOI/BiOIO3 nanocomposites unfold drastically strengthened photoreactivity, in which the MB degradation rate is over 85% for 1 h irradiation, and the photocurrent density rises more than 3 times higher than the pristine sample. This enhancement should be ascribed to the formation of a steady p–n junction between the n-type BiOIO3 and p-type BiOI as well as dominantly exposed reactive facets. Separation and transfer of photoinduced charges are thereby greatly boosted as verified by the electrochemical and photoelectrochemical results. This work paves a novel way for fabrication of semiconductor p–n junction via composition transformation and furnishes a new perspective into the designing of crystal reactive facet.
Co-reporter:Jingwen Feng, Hongwei Huang, Shixin Yu, Fan Dong and Yihe Zhang
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 11) pp:7851-7859
Publication Date(Web):15 Feb 2016
DOI:10.1039/C5CP06685A
The development of high-performance visible-light photocatalysts with a tunable band gap has great significance for enabling wide-band-gap (WBG) semiconductors visible-light sensitive activity and precisely tailoring their optical properties and photocatalytic performance. In this work we demonstrate the continuously adjustable band gap and visible-light photocatalysis activation of WBG BiOIO3via iodine surface modification. The iodine modified BiOIO3 was developed through a facile in situ reduction route by applying BiOIO3 as the self-sacrifice template and glucose as the reducing agent. By manipulating the glucose concentration, the band gap of the as-prepared modified BiOIO3 could be orderly narrowed by generation of the impurity or defect energy level close to the conduction band, thus endowing it with a visible light activity. The photocatalytic assessments uncovered that, in contrast to pristine BiOIO3, the modified BiOIO3 presents significantly boosted photocatalytic properties for the degradation of both liquid and gaseous contaminants, including Rhodamine B (RhB), methyl orange (MO), and ppb-level NO under visible light. Additionally, the band structure evolution as well as photocatalysis mechanism triggered by the iodine surface modification is investigated in detail. This study not only provides a novel iodine surface-modified BiOIO3 for environmental application, but also provides a facile and general way to develop highly efficient visible-light photocatalysts.
Co-reporter:Na Tian, Yihe Zhang, Chengyin Liu, Shixin Yu, Min Li and Hongwei Huang
RSC Advances 2016 vol. 6(Issue 13) pp:10895-10903
Publication Date(Web):21 Jan 2016
DOI:10.1039/C5RA24672E
We disclose the fabrication of 2D–2D heterojunctional nanosheets g-C3N4/Bi4O5I2 photocatalyst by using a mixed-calcination method. This synthetic method enables intimate interfacial interaction between g-C3N4 and Bi4O5I2, which is beneficial for charge transfer at the interface. The photocatalysis properties of g-C3N4/Bi4O5I2 composites were studied by photodegradation of Rhodamine B (RhB) and NO removal under visible-light (λ > 420 nm) irradiation. The results revealed that the g-C3N4/Bi4O5I2 composites show enhanced photocatalytic activity compared to the pristine g-C3N4 and Bi4O5I2 samples. Investigations on the behaviours of charge carriers via photoluminescence (PL) spectra and transient photocurrent responses suggest that the g-C3N4/Bi4O5I2 heterostructure is responsible for the efficient separation and transfer of photogenerated electron–hole pairs, thus giving rise to the higher photocatalytic activity. The formation of 2D–2D heterostructured n–n type g-C3N4/Bi4O5I2 composites as well as photocatalytic mechanism was verified by a series of combined techniques, including the active species trapping experiments and Mott–Schottky plots. The present work furthered our understanding on fabrication of homogeneous heterojunction photocatalyst.
Co-reporter:Yueyun Li, Yihe Zhang, Liping Jiang, Paul K. Chu, Ynhui Dong and Ping Wang
RSC Advances 2016 vol. 6(Issue 9) pp:6932-6938
Publication Date(Web):18 Jan 2016
DOI:10.1039/C5RA26142B
An ultrasensitive electrochemical immunosensor is designed and constructed for the quantitative detection of squamous cell carcinoma antigens (SCCAs). Silver nanoparticles (AgNPs) hybridized and 3-aminopropyltriethoxysilane functionalized graphene sheets (Ag@APTES-GS) serve as the platform to immobilize primary antibodies (Ab1). The mesoporous AgNPs-decorated silica KIT-6 (Ag@KIT-6) with a large specific surface area is utilized to label the electron mediator thionin (TH) and secondary antibodies (Ab2) by physical adsorption and chemical bonding. Carboxymethyl chitosan (CMC) doped with ionic liquids (ILs) is used to facilitate electron transfer and prevent leaking of TH resulting in multiple signal amplification. In addition to the excellent detection limit (17 fg mL−1, S/N = 3) and wide linear range (5 × 10−5 ng mL−1 to 102 ng mL−1), the immunosensor shows good selectivity, reproducibility, and stability. Providing quantitative detection of SCCA in serum, the sensor has great potential in clinical and diagnostic applications.
Co-reporter:Xue Chen, Qidi Wang, Fengzhu Lv, Paul K. Chu and Yihe Zhang
RSC Advances 2016 vol. 6(Issue 14) pp:11211-11217
Publication Date(Web):14 Jan 2016
DOI:10.1039/C5RA25124A
A series of novel double-phosphate compounds RbCaGd(PO4)2:Eu2+ were first synthesized by the Pechini-type sol–gel method, and their structure and luminescence properties were characterized in detail. The compound RbCa0.97Gd(PO4)2:0.03Eu2+ crystallizes in the hexagonal system with space group P6222 and the parameters a = 7.006(49) Å, c = 6.358(80) Å, and V = 269.969 Å3, Z = 1. Its crystal structure is similar to that of hexagonal LnPO4, where the Rb atom occupies a large tunnel in the lattice and the Ln position is statistically occupied by both Gd and Ca (Eu) atoms. In addition, RbCaGd(PO4)2:Eu2+ produces an intense broadband emission from 400 to 600 nm with the CIE coordinates near (0.2089, 0.2674) and assembles a broad excitation spectrum from 250 to 425 nm. The concentration quenching, crystal field splitting, critical energy transfers distance and thermally stable luminescence properties of RbCaGd(PO4)2:Eu2+ phosphors are all discussed, which indicate that this material can be considered as a promising bluish green phosphor for application in white-light UV LEDs.
Co-reporter:Ling Ding, Yihe Zhang, Leipeng Liu, Jianshe Hu and Fengzhu Lv
RSC Advances 2016 vol. 6(Issue 62) pp:56812-56818
Publication Date(Web):06 Jun 2016
DOI:10.1039/C6RA10244A
Poly(amic acid) composite films with the thermotropic liquid crystal, 10-cholesteroxy-10-oxocaproic acid (COOA) were developed. The composites could still show liquid crystal behavior at low COOA loading (as low as 3 wt%) due to the phase separation under the induction of temperature. The synergistic reaction of the interaction of PAA with COOA and the arrangement of COOA endowed the films with strong fluorescence and a higher temperature shifted liquid crystal phase. Even more, the dielectric constant of the composites was enhanced. The composites were multifunctional optical-electric materials.
Co-reporter:Zilin Meng, Fengzhu Lv, Xiaowei Li, Qian Zhang, Paul K. Chu, Sridhar Komarneni, Yihe Zhang
Microporous and Mesoporous Materials 2016 Volume 227() pp:137-143
Publication Date(Web):June 2016
DOI:10.1016/j.micromeso.2016.02.046
•A recyclable process was developed for arsenate removal and alkali reduction.•Removal of alkali and As simultaneously from waste water by one-pot method.•Selective uptake of arsenate from other anions was related to bonding energies.•The removal and release processes of arsenate were accomplished by cycling.An effective and facile method was developed to remove As(V) and alkali simultaneously from alkaline wastewater based on the repeated in-situ formation of Zn–Al–AsO4 layered double hydroxide (ZnAl–AsO4 LDH). The removal efficiency of As(V) was almost 100% and the pH of the treated alkaline wastewater decreased from 12 to 7.47. Removal of As(V) was not affected by competitive anions such as SO42−, F−, Cl−, and NO3− due to the large binding energy between As(V) and LDH sheets as confirmed by calculations based on the Castep Module of Materials. About 96% of As(V) can be released and concentrated into a small volume of Na2CO3 solution for disposal or recovery. The LDH was then dissolved in HNO3 and the solution can be used to treat wastewater to reform Zn–Al LDH for further removal of arsenate. This process was repeated four times but after the fifth cycle, the removal efficiency went down by the loss of Al3+ to solution but the process can be repeated by replenishing the solution with Al3+. The newly developed process is eminently suited for remediation of arsenate and alkali simultaneously from alkaline wastewater.
Materials Science in Semiconductor Processing 2016 Volume 41() pp:317-322
Publication Date(Web):January 2016
DOI:10.1016/j.mssp.2015.09.021
Two novel visible-light-responsive bismuth oxychloride photocatalysts Bi2EuO4Cl and Bi2NdO4Cl have been successfully developed via a solid-state reaction route. Their crystal structures and optical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), diffuse reflectance spectra (DRS), and photoluminescence (PL) spectra. Fascinatingly, both the compounds possess considerable optical absorption in a broad region ranging from UV light to visible light. The indirect-transition optical band gaps of Bi2EuO4Cl and Bi2NdO4Cl are estimated to be 2.21 and 1.89 eV, respectively. For the first time, their photocatalytic activities were determined by photodecomposition of methylene blue (MB) in aqueous solution under visible light (λ>420 nm). The results revealed that both Bi2EuO4Cl and Bi2NdO4Cl can be used as effective visible-light-driven photocatalysts. In addition, theoretical calculations on the electronic structure, orbital constitutions and optical absorption of Bi2NdO4Cl were also performed. These findings shed light on the exploration of new photocatalytic materials activated by visible light.
•A layered Bi-based compound LiBi3O4Cl2 is researched as new photocatalysts.•It is synthesized by a simple solid-state reaction.•It can effectively degrade azo dye and phenol under light irradiation.•OH and h+ as active species play important roles in degradation process.Developing new photocatalysts is of significant importance for their potential environmental and energetic applications. Herein, a novel layered bismuth-based photocatalytic material LiBi3O4Cl2 was developed by a simple solid-state reaction. The morphology, microstructures and optical properties were investigated by XRD, SEM, TEM and DRS. The band gap of LiBi3O4Cl2 has been determined to be 3.35 eV, and its ECB and EVB were also estimated. The photocatalytic property of LiBi3O4Cl2 is surveyed by oxidative decomposition of rhodamine B (RhB), methyl orange (MO), methylene blue (MB) and phenol in aqueous solution. The results demonstrated that LiBi3O4Cl2 is an efficient UV light active photocatalyst, which can destroy the contaminants with irradiation. It is also more effective in degrading pollutants than the related layered bismuth-based photocatalyst Bi4NbO8Br. The photocatalysis mechanism is detailedly investigated by active species trapping measurement and terephthalic acid photoluminescence probing technique (TA-PL). It revealed that powerful hydroxyl radicals (OH) and photogenerated holes (h+) are the two main active species and are responsible for the efficient degradation process. This study provides a new layered bismuth-based photocatalytic material for environmental and energetic applications.A novel layered photocatalyst LiBi3O4Cl2 has been developed for efficient photodecomposition of contaminants. The photocatalytic mechanism was also investigated.
Co-reporter:Ke Xiao, Hongwei Huang, Na Tian, Yihe Zhang
Materials Research Bulletin 2016 Volume 83() pp:172-178
Publication Date(Web):November 2016
DOI:10.1016/j.materresbull.2016.05.016
Bi2MoO6/g-C3N4 composites were synthesized by a mixed-calcination method.The Bi2MoO6/g-C3N4 photocatalyst exhibits much better photocatalytic performance.The enhanced photocatalytic activity is attributed to the hetrojunction structure.Holes (h+) and superoxide radicals (O2⿿) serve as the two main active species.Organic-inorganic hybrid photocatalyst Bi2MoO6/g-C3N4 was synthesized via a mixed-calcination route based on intimate interfacial interaction. The successful combination of g-C3N4 and Bi2MoO6 was verified by X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) mapping. The optical property of the as-prepared photocatalysts was characterized by UV⿿vis diffuse reflectance spectra (DRS). The photocatalytic activities were investigated by degradation of Rhodamine B (RhB) and photocurrent generation under visible-light (λ > 420 nm). The results demonstrated that the Bi2MoO6/g-C3N4 composite exhibits highly enhanced photoreactivity compared to the pristine samples. It should be attributed to the fabrication of a Bi2MoO6/g-C3N4 heterojunction, thus resulting in the high separation and transfer efficiency of photogenerated charge carriers, as confirmed by the photoluminescence (PL) and electrochemical impedance spectra (EIS). The active species trapping experiments indicated that holes (h+) and superoxide radicals (O2⿿) are the main active species in the degradation process.
Co-reporter:Xinglong Luan;Dr. Yihe Zhang;Dr. Jing Wu;Dr. Pascal Jonkheijm;Dr. Guangtao Li;Dr. Lei Jiang;Dr. Jurriaan Huskens;Dr. Qi An
ChemistryOpen 2016 Volume 5( Issue 4) pp:331-338
Publication Date(Web):
DOI:10.1002/open.201600030
Abstract
The kinetics of supramolecular bindings are fundamentally important for molecular motions and spatial–temporal distributions in biological systems, but have rarely been employed in preparing artificial materials. This report proposes a bio-inspired concept to regulate dynamic gradients through the coupled supramolecular binding and diffusion process in receptor-embedded hydrogel matrices. A new type of hydrogel that uses cyclodextrin (CD) as both the gelling moiety and the receptors is prepared as the diffusion matrices. The diffusible guest, 4-aminoazobenzene, quickly and reversibly binds to matrices-bound CD during diffusion and generates steeper gradients than regular diffusion. Weakened bindings induced through UV irradiation extend the gradients. Combined with numerical simulation, these results indicate that the coupled binding–diffusion could be viewed as slowed diffusion, regulated jointly by the binding constant and the equilibrium receptor concentrations, and gradients within a bio-relevant extent of 4 mm are preserved up to 90 h. This report should inspire design strategies of biomedical or cell-culturing materials.
The Journal of Physical Chemistry C 2016 Volume 120(Issue 19) pp:10381-10389
Publication Date(Web):April 29, 2016
DOI:10.1021/acs.jpcc.6b01705
Metal-free graphitic carbon nitride (g-C3N4) shows benign photocatalytic abilities concerning contaminant decomposition and hydrogen evolution under visible light irradiation. Developing facile modification tactics for promoted activity of g-C3N4 has always been desirable and worth pursuing. Herein, we report the integration of multiple (three-in-one) advantageous effects in g-C3N4 photocatalyst by a simple co-pyrolyzation of co-precursors melamine and NH4HCO3. This strategy utilizing NH4HCO3 as a bubble soft template not only endows g-C3N4 with porous structure with enhanced specific surface area, but also renders highly promoted separation and transfer of charge carriers and up-shifted conduction band. Given these benefits, the modified g-C3N4 unfolds remarkably improved photocatalytic performance toward RhB degradation, NO removal, and hydrogen evolution. Additionally, the exploration on active radicals has also corroborated the ameliorated band structure and illustrates the photocatalytic mechanism. Our present work may open up a new avenue for ameliorating the photocatalytic property of g-C3N4 and also further our understanding of design of high-performance photoelectric materials.
Co-reporter:Baoying Li, Yihe Zhang, Ruifeng Du, Lin Gan, and Xuelian Yu
Langmuir 2016 Volume 32(Issue 44) pp:11639-11645
Publication Date(Web):October 18, 2016
DOI:10.1021/acs.langmuir.6b03213
In this article, novel types of Bi2S3–Au heterostructures are fabricated through rationally controlling the growth atmosphere. Under argon, Au nanoparticles are preferentially deposited onto the tips of Bi2S3 nanorods to form Bi2S3–Au dumbbell heterostructures. In contrast, because of the etching effect by amine, Au nanoparticles are randomly anchored onto the surface of nanorods to form Bi2S3–Au nanocorns in the presence of oxygen. Furthermore, the size of gold nanoparticles can be controlled through adjusting the concentration of reaction precursors. Bi2S3–Au dumbbells show superior activity for the photodegradation of organic pollutants and an enhanced photoresponse compared to the Bi2S3–Au nanocorns. The significantly improved photocatalytic performance of Bi2S3–Au dumbbells is ascribed to the more efficient charge separation compared to that of Bi2S3–Au nanocorns. These heterostructures composed of environmentally friendly elements are expected to be promising for applications in the field of clean energy.
Co-reporter:Huan Wang, Yihe Zhang, Yanguang Chu, Hongmin Ma, Yan Li, Dan Wu, Bin Du, Qin Wei
Talanta 2016 Volume 147() pp:556-560
Publication Date(Web):15 January 2016
DOI:10.1016/j.talanta.2015.10.040
•Metal ions were used as the signal tags.•Copper ions were released from Cu-apatite through acidic dissolution.•AFB1 detection based on stripping voltammetric detection of copper ions.A disposable electrochemical immunosensor was developed for detection of aflatoxin B1 (AFB1) based on stripping voltammetric detection of copper ions released from Cu-apatite. AFB1 antibody (Ab) was firstly fixed on the gold nanoparticle (Au NPs) modified screen-printed carbon electrode (SPCE). AFB1-bovine serum albumin (AFB1-BSA) conjugate was labeled with Cu-apatite, and then competed with AFB1 for binding to the Ab. Copper ions were released from Cu-apatite through acidolysis and stripping voltammetry signal of the copper ions was used for the detection. The Cu-apatite increased the amount of loaded copper ions, and the anodic stripping strategy performed in the micro electrolytic cell of the SPCE simplified the detection procedure and further amplified the electrochemical signal. This immunosensor could detect AFB1 over a wide concentration range from 0.001 to 100 ng mL−1 with a detection limit of 0.2 pg mL−1. The low cost, high sensitive, rapid and accurate method may find widely potential application in the detection of other toxic or harmful substances.
Co-reporter:Leipeng Liu, Fengzhu Lv, Penggang Li, Ling Ding, Wangshu Tong, Paul K. Chu, Yihe Zhang
Composites Part A: Applied Science and Manufacturing 2016 Volume 84() pp:292-298
Publication Date(Web):May 2016
DOI:10.1016/j.compositesa.2016.02.002
Ultra-low dielectric constant silica/polyimide (SiO2/PI) composite nanofiber membranes are prepared by the combined sol–gel and electrospinning techniques. The emulsion composed of partially hydrolyzed tetraethoxysilane (TEOS) and polyamic acid (PAA) is spun to yield the precursor of the SiO2/PI fibers with a core–shell structure due to phase separation. The dielectric constant (k) of the composite membranes varies from 1.78 to 1.32 with increasing content of SiO2. The fibers accumulate and form the film with a large amount of pores leading the lower k. In addition, the interfacial reaction between SiO2 and the PI matrix reduces the value of k as the SiO2 concentration is increased. The thermal stability of PI increase after mixing with SiO2 and the SiO2/PI composite fibers have large commercial potential in the electronics industry.
Co-reporter:Hongwei Huang, Ke Xiao, Na Tian, Xin Du, Yihe Zhang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 511() pp:64-72
Publication Date(Web):20 December 2016
DOI:10.1016/j.colsurfa.2016.09.063
•(CO3)2− self-doped Bi2O2CO3/g-C3N4 composites are synthesized.•Due to charge attraction, 2D-2D Bi2O2CO3/g-C3N4 heterostructure is formed.•The composites show highly enhanced photocatalytic activity for RhB degradation.•High charge transfer efficiency is responsible for the photoactivity enhancement.The (CO3)2− self-doped Bi2O2CO3/g-C3N4 (C-BOC/g-C3N4) unique 2D-2D heterostructure has been developed via a mixed-calcination method. This heterostructure is confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), SEM-mapping, and diffuse reflection spectroscopy (DRS). Due to the charge interaction, it is interesting to observe that C-BOC nanosheets are assembled on g-C3N4 in a surface–surface coupling way, which enables an intimate interfacial interaction between the two components. The photocatalytic activity is evaluated by photodegradation of Rhodamine B (RhB) under visible light (λ > 420 nm). It is found that all the C-BOC/g-C3N4 composites showed highly enhanced photocatalytic activity. Electrochemical impedance spectra (EIS) measurement revealed that the largely promoted charge transfer derived from the well matchable band structure and intimate interfacial interactions between the two visible-light active components is responsible for the photoactivity enhancement. Besides, the active species trapping and O2− quantitation experiments are conducted to disclose the photocatalytic mechanism.(CO3)2− self-doped Bi2O2CO3/g-C3N4 2D-2D heterostructure is synthesized and its shows highly enhanced visible-light photocatalytic activity.
An all-solid-state flexible generator–capacitor polymer composite film converts low-frequency biomechanical energy into stored electric energy. This design, which combines the functionality of a generator with a capacitor, is realized by employing poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) in the simultaneous dual role of piezoelectric generator and polymer matrices of the flexible capacitor. Proper surface modification of the reduced graphene oxide (rGO) fillers in the polymeric matrices is indispensable in achieving the superior energy storage performance of the composite film. The heightened dielectric performance stems from enhanced compatibility of the rGO fillers and PVDF-HFP matrices, and a microcapacitor model properly explains the dielectric behaviors. A device that is easily fabricated using our film allows timely decoupled motion energy harvest and output of the motion-generated electricity. This report opens new design possibilities in the fields of motion sensors, information storage and high-voltage output by accumulating low-frequency random biological motions.
Co-reporter:Hongwei Huang, Xiaowei Li, Jinjian Wang, Fan Dong, Paul K. Chu, Tierui Zhang, and Yihe Zhang
ACS Catalysis 2015 Volume 5(Issue 7) pp:4094
Publication Date(Web):June 3, 2015
DOI:10.1021/acscatal.5b00444
We herein demonstrate self-doping of the CO32– anionic group into a wide bandgap semiconductor Bi2O2CO3 realized by a one-pot hydrothermal technique. The photoresponsive range of the self-doped Bi2O2CO3 can be extended from UV to visible light and the band gap can be continuously tuned. Density functional theory (DFT) calculation results demonstrate that the foreign CO32– ions are doped in the caves constructed by the four adjacent CO32– ions and the CO32– self-doping can effectively narrow the band gap of Bi2O2CO3 by lowering the conduction band position and meanwhile generating impurity level. The photocatalytic performance is evaluated by monitoring NO removal from the gas phase, photodegradation of a colorless contaminant (bisphenol A, BPA) in an aqueous solution, and photocurrent generation. In comparison with the pristine Bi2O2CO3 which is not sensitive to visible light, the self-doped Bi2O2CO3 exhibits drastically enhanced visible-light photoreactivity, which is also superior to that of many other well-known photocatalysts such as P25, C3N4, and BiOBr. The highly enhanced photocatalytic performance is attributed to combination of both efficient visible light absorption and separation of photogenerated electron–hole pairs. The self-doped Bi2O2CO3 also shows decent photochemical stability, which is of especial importance for its practical applications. This work demonstrates that self-doping with an anionic group enables the band gap engineering and the design of high-performance photocatalysts sensitive to visible light.Keywords: band gap; Bi2O2CO3; charge separation; photocatalysis; self-doping
Co-reporter:Qian Zhang, Qi An, Xinglong Luan, Hongwei Huang, Xiaowei Li, Zilin Meng, Wangshu Tong, Xiaodong Chen, Paul K. Chu and Yihe Zhang
Nanoscale 2015 vol. 7(Issue 33) pp:14002-14009
Publication Date(Web):20 Jul 2015
DOI:10.1039/C5NR03256C
A high-performance visible-light-active photocatalyst is prepared using the polyelectrolyte/exfoliated titania nanosheet/graphene oxide (GO) precursor by flocculation followed by calcination. The polyelectrolyte poly(diallyl-dimethyl-ammonium chloride) serves not only as an effective binder to precipitate GO and titania nanosheets, but also boosts the overall performance of the catalyst significantly. Unlike most titania nanosheet-based catalysts reported in the literature, the composite absorbs light in the UV-Vis-NIR range. Its decomposition rate of methylene blue is 98% under visible light. This novel strategy of using a polymer to enhance the catalytic performance of titania nanosheet-based catalysts affords immense potential in designing and fabricating next-generation photocatalysts with high efficiency.
Co-reporter:Hongwei Huang, Ying He, Xiaowei Li, Min Li, Chao Zeng, Fan Dong, Xin Du, Tierui Zhang and Yihe Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 48) pp:24547-24556
Publication Date(Web):12 Nov 2015
DOI:10.1039/C5TA07655B
Developing high-performance photocatalytic materials is of huge significance and highly desirable for fulfilling the pressing need in environmental remediation. In this work, we demonstrate the use of bismuth nitrate Bi2O2(OH)(NO3) as an absorbing photocatalyst, which integrates multiple superiorities, like a [Bi2O2]2+ layered configuration, a non-centrosymmetric (NCS) polar structure and highly reactive {001} facets. Bi2O2(OH)(NO3) nanosheets are obtained by a facile one-pot hydrothermal route using Bi(NO3)3·5H2O as the sole raw material. Photocatalysis assessment revealed that Bi2O2(OH)(NO3) holds an unprecedented photooxidation ability in contaminant decomposition, far out-performing the well-known photocatalysts BiPO4, Bi2O2CO3, BiOCl and P25 (commercial TiO2). Particularly, it displays a universally powerful catalytic activity against various stubborn industrial contaminants and pharmaceuticals, including phenol, bisphenol A, 2,4-dichlorophenol and tetracycline hydrochloride. In-depth experimental and density functional theory (DFT) investigations co-uncovered that the manifold advantages, such as large polarizability and rational band structure, as well as exposed {001} active facets, induced robust generation of strong oxidating superoxide radicals (˙O2−) in the conduction band and hydroxyl radicals (˙OH) in the valence band, thus enabling Bi2O2(OH)(NO3) to have a powerful and durable photooxidation capability. Bi2O2(OH)(NO3) also presents high photochemical stability. This work not only rendered a highly active and stable photocatalyst for practical applications, but also laid a solid foundation for future initiatives aimed at designing new photoelectronic materials by manipulating multiple advantageous factors.
Co-reporter:Na Tian, Hongwei Huang, Chengyin Liu, Fan Dong, Tierui Zhang, Xin Du, Shixin Yu and Yihe Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 33) pp:17120-17129
Publication Date(Web):14 Jul 2015
DOI:10.1039/C5TA03669K
Development of efficient photocatalysts with both photoinduced oxidation and reduction properties is of great importance for environmental and energy applications. Herein, we report the fabrication of CeO2/g-C3N4 hybrid materials by a simple in situ co-pyrolysis method using Ce(IO3)3 and melamine as precursors. The CeO2/g-C3N4 composite catalysts possess outstanding photocatalytic activity for phenol degradation and NO removal under visible light irradiation. The degradation efficiency reaches up to 68.5 and 17.3 times higher than that of pure CeO2 and g-C3N4, respectively. Significantly, it simultaneously exhibits an enhanced hydrogen production rate, which is 1.5 times that of the pure g-C3N4. The highly enhanced photo-induced oxidation and reduction activity could be attributed to the construction of a CeO2/g-C3N4 n–n type heterojunction established by our in situ co-pyrolysis route, which enables intimate interaction across the phase interfaces; this facilitates separation and transfer of photoexcited charge carriers. This study could not only provide a facile and general approach to the fabrication of high-performance carbon-nitride-based photocatalytic materials, but also increase our understanding further on designing new hybrid composite photocatalysts for multi-functional applications.
Co-reporter:Yuxi Guo, Hongwei Huang, Ying He, Na Tian, Tierui Zhang, Paul K. Chu, Qi An and Yihe Zhang
Nanoscale 2015 vol. 7(Issue 27) pp:11702-11711
Publication Date(Web):26 May 2015
DOI:10.1039/C5NR02246K
We demonstrate the fabrication of a core–satellite structured BiOBr–CdS photocatalyst with highly efficient photocatalytic reactivity via a facile in situ crystallization approach at room temperature. The transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) results reveal that the BiOBr flakes are surrounded by CdS particles. The coverage of the satellites on the surface of the BiOBr nanosheets could be controlled by changing the content of the CdS, which contributes to the enhanced level of photocatalytic performance. The UV–vis diffuse reflection spectra demonstrate that the visible light absorption of the BiOBr–CdS photocatalyst is also enhanced by the CdS loaded. The excellent structural and spectral properties endow the BiOBr–CdS heterojunctions with improved photocatalytic performance pertaining to bisphenol A (BPA) degradation and photocurrent generation. Under visible light irradiation, the optimum photocatalytic activity of BiOBr–CdS at a molar ratio of 1:5 (CdS/BiOBr) is almost 2.8 times and 24.6 times as high as that of pure BiOBr and CdS. The remarkably enhanced photoreactivity should be attributed to the match in the energy levels and close core–satellite structural coupling between the CdS and BiOBr, which greatly facilitates the separation and transfer of photoinduced electron–hole pairs, as confirmed by photoluminescence (PL) and electrochemical impedance spectra (EIS). The present work sheds new light on the construction of highly efficient core–satellite heterojunctional photocatalysts for practical applications.
Herein, we uncover simultaneously achieving plasmonic Bi metal deposition and I– doping by employing wide-band-gap BiOIO3 as the self-sacrificing template. It was synthesized via a facile NaBH4-assisted in situ reduction route under ambient conditions. The reducing extent as well as photocatalytic levels can be easily modulated by controlling the concentration of NaBH4 solution. It is interesting that the band gap of BiOIO3 can be continuously narrowed by the modification, and the photoresponse range is drastically extended to cover the whole visible region. Bi/I– codecorated BiOIO3 not only exhibits profoundly upgraded photoreactivity in comparison with pristine BiOIO3 but also shows universally strong photooxidation properties toward decomposition of multiple industrial contaminants and pharmaceutical, including phenol, 2,4-Dichlorophenol (2,4-DCP), bisphenol A (BPA), dye model Rhodamine (RhB), tetracycline hydrochloride, and gaseous NO under visible light (λ ≥ 420 nm) or simulated solar light irradiation. It also outperforms the well-known and important photocatalysts C3N4, BiOBr, and Bi2WO6 for NO removal. The cooperative effects from Bi SPR and I– doping endow BiOIO3 with a narrowed band gap and highly boosted separation of charge carriers, thus responsible for the outstanding catalytic activity. The present study provides an absorbing candidate for practical environmental applications and also furthers our understanding of developing high-performance photocatalysts by manipulating manifold strategies in a facile way.Keywords: Bi deposition; I doping; in situ reduction; photoabsorption; photocatalysis
To take full advantage of sunlight for photomechanical materials, NIR–vis–UV light-responsive actuator films of polymer-dispersed liquid crystal (PDLC)/graphene oxide (GO) nanocomposites were fabricated. The strategy is based on phase transition of LCs from nematic to isotropic phase induced by combination of photochemical and photothermal processes in the PDLC/GO nanocomposites. Upon mechanical stretching of the film, both topological shape change and mesogenic alignment occurred in the separated LC domains, enabling the film to respond to NIR–vis–UV light. The homodispersed GO flakes act as photoabsorbent and nanoscale heat source to transfer NIR or VIS light into thermal energy, heating the film and photothermally inducing phase transition of LC microdomains. By utilizing photochemical phase transition of LCs upon UV-light irradiation, one azobenzene dye was incorporated into the LC domains, endowing the nanocomposite films with UV-responsive property. Moreover, the light-responsive behaviors can be well-controlled by adjusting the elongation ratio upon mechanical treatment. The NIR–vis–UV light-responsive PDLC/GO nanocomposite films exhibit excellent properties of easy fabrication, low-cost, and good film-forming and mechanical features, promising their numerous applications in the field of soft actuators and optomechanical systems driven directly by sunlight.Keywords: GO nanocomposites; light-responsive actuator; liquid crystal and nanocomposites; photomechanical materials; polymer-dispersed liquid crystals
A stable drug release system with magnetic targeting is essential in a drug delivery system. In the present work, layered double hydroxide assemblies stabilized by layer-by-layer polymer multilayers were prepared by alternative deposition of poly(allylamine hydrochloride) and poly(acrylic acid) species on composite particles of Fe3O4 and ZnAl-LDH and then covalent cross-linkage of the polymer multilayers by photosensitive cross-linker. The successful fabrication was recorded by Zeta potential and Fourier transform infrared spectrum measurements. The formed assemblies were stable in high pH solutions (pH > 7). The drug loading capacity and release behavior of the assemblies could be controlled by treatment with appropriate acidic solution, and were confirmed by loading and release of a simulated drug, methylene blue. The formed assemblies possessed enough saturated magnetic strength and were sensitive to external magnetic field which was essential for targeting drug delivery. The formed assemblies were multifunctional assemblies with great potential as drug delivery system.Keywords: controlled drug release; covalent stabilization; etching; layer-by-layer; Layered double hydroxide
To fabricate functionally integrated hybrid nanoparticles holds high importance in biomedical applications and is still a challenging task. In this study, we report the first reduced graphene oxide (rGO)-nobel metal hybrid particles that present simultaneously the photothermal and surface-enhanced Raman spectroscopy (SERS) effect from the inorganic part and drug loading, dispersibility, and controllability features from LbL polyelectrolyte multilayers. The hybrid particles where spiky noble metal particles were wrapped within rGO-polyelectrolyte layers were prepared by a facile and controllable method. rGO template modified using polyethylenimine (PEI) and poly(acrylic acid) (PAA) via layer-by-layer technology served as the reactive precursors, and the morphologies of the particles could be facilely controlled via controlling the number of bilayers around the rGO template. The hybrid particle presented low cytotoxicity. After loading doxorubicin hydrochloride, the particles effectively induced cell death, and photothermal treatment further decreased cell viability. rGO-Ag hybrid particles could be prepared similarly. We expect the reported method provides an effective strategy to prepare rGO-noble metal hybrid nanoparticles that find potential biomedical applications.Keywords: gold nanoparticles; graphene; hybrid nanoparticles; layer-by-layer; photothermal; surface-enhanced Raman scattering
The fabrication of multiple heterojunctions with tunable photocatalytic reactivity in full-range BiOBr–BiOI composites based on microstructure modulation and band structures is demonstrated. The multiple heterojunctions are constructed by precipitation at room temperature and characterized systematically. Photocatalytic experiments indicate that there are two types of heterostructures with distinct photocatalytic mechanisms, both of which can greatly enhance the visible-light photocatalytic performance for the decomposition of organic pollutants and generation of photocurrent. The large separation and inhibited recombination of electron–hole pairs rendered by the heterostructures are confirmed by electrochemical impedance spectra (EIS) and photoluminescence (PL). Reactive species trapping, nitroblue tetrazolium (NBT, detection agent of •O2–) transformation, and terephthalic acid photoluminescence (TA-PL) experiments verify the charge-transfer mechanism derived from the two types of heterostructures, as well as different enhancements of the photocatalytic activity. This article provides insights into heterostructure photocatalysis and describes a novel way to design and fabricate high-performance semiconductor composites.Keywords: BiOBr; BiOI; crystal structure; electronic structure; photocatalytic mechanism
Development of core/shell heterostructures and semiconductor p–n junctions is of great concern for environmental and energy applications. Herein, we develop a facile in situ deposition route for fabrication of a BiVO4/BiOI composite integrating both the core/shell heterostructure and semiconductor p–n junction at room temperature. In the BiVO4/BiOI core/shell heterostructure, the BiOI nanosheets are evenly assembled on the surface of the BiVO4 cores. The photocatalytic performance is evaluated by monitoring the degradation of the dye model Rhodamine B (RhB), colorless contaminant phenol, and photocurrent generation under visible-light irradiation. The heterostructured BiVO4/BiOI core/shell photocatalyst shows drastically enhanced photocatalysis properties compared to the pristine BiVO4 and BiOI. This remarkable enhancement is attributed to the intimate interfacial interactions derived from the core/shell heterostructure and formation of the p–n junction between the p-type BiOI and n-type BiVO4. Separation and transfer of photogenerated electron–hole pairs are hence greatly facilitated, thereby resulting in the improved photocatalytic performance as confirmed by electrochemical, photoelectrochemical, radicals trapping, and superoxide radical (•O2–) quantification results. Moreover, the core/shell BiVO4/BiOI also displays high photochemical stability. This work sheds new light on the construction of high-performance photocatalysts with core/shell heterostructures and matchable band structures in a simple and efficient way.Keywords: BiOI; BiVO4; Core/shell heterostructures; Photocatalysis; p−n junction
Co-reporter:Zhentao Cui, Shuguang Wang, Yihe Zhang, Minhua Cao
Electrochimica Acta 2015 Volume 182() pp:507-515
Publication Date(Web):10 November 2015
DOI:10.1016/j.electacta.2015.09.120
Co3O4 has been investigated intensively for its high specific capacity which makes it a promising candidate anode for high-performance lithium ion batteries (LIBs). However, rational design of Co3O4 electrode that is beneficial for its electrochemical performance is still a great challenge. Herein, we designed and fabricated porous Co3O4 nanotubes (P-Co3O4-NTs) by coaxial electrospinning method followed by a fine annealing treatment, which display one dimensional tubular structure with porous wall and hollow interior. The uniqueness of this strategy is that the morphologies of the P-Co3O4-NTs could be tuned by adjusting the mass ratio of reactants. The resultant P-Co3O4-NTs exhibit excellent lithium storage performance in terms of specific capacity, rate capability, and cycling stability, when used as an anode material for rechargeable LIBs. This unique structure endows a high reversible specific capacity of 1826.2 mA g−1 at a current density of 0.3 A g−1 after 100 cycles. Even at high current densities of 2 and 5 A g−1, the P-Co3O4-NTs electrode still could deliver remarkable discharge capacities of 1506.2 and 1145.1 mAh g−1, respectively. The excellent electrochemical performance can be attributed to the unique tubular and porous structure of P-Co3O4-NTs, which not only can accommodate the large volume change but also can provide an excellent ion diffusion and electronic conduction pathway. Therefore, the P-Co3O4-NTs have the potential for use as a high performance anode material in LIBs.The porous Co3O4 nanotubes (P-Co3O4-NTs) are prepared by coaxial electrospinning method followed by a fine annealing treatment. The resultant P-Co3O4-NTs exhibit excellent lithium storage performance in terms of specific capacity, rate capability, and cycling stability when used as an anode material for rechargeable lithium ion batteries (LIBs).
Herein we report the Bi2O2CO3 single-crystal nanoplates with dominant {001} exposing facets fabricated via a controllable hydrothermal means. Exposed {001} reactive facets enable BOC-001 nanoplates efficient separation and migration of photoinduced electron–hole pairs, thereby resulting in highly enhanced photoreactivity pertaining to rhodamine B degradation, NO removal, and photocurrent generation. The present work provides a new reference for manipulation of facet-dependent photocatalytic activity of semiconductors.
Co-reporter:Qi An, Kun Nie, Yihe Zhang, Yue Wang, Yingmo Hu, Victoria Dutschk and Xinglong Luan
Soft Matter 2015 vol. 11(Issue 34) pp:6859-6865
Publication Date(Web):28 Jul 2015
DOI:10.1039/C5SM01647A
A “nano-net” superstratum strategy is developed to stabilize layer-by-layer (LbL) films that incorporate nanoparticles. The superstratum immobilizes silica, gold, or magnetic nanoparticles and at the same time is permeable to small molecules. Unlike most strategies to stabilize LbL multilayers reported in the literature, our strategy does not directly cross-link the nanoparticles and polymers in the adjacent layer, thus circumventing the tedious processes of (surface) modification of the nanoparticles or polymers. The unique advantage of our strategy is further employed in the preparation of a model functional device, where mesoporous silica nanoparticles are held in the composite multilayers with enhanced stabilities. A model drug, methylene blue, is then loaded in large amounts due to the porous structure of the silica particles, and could be released in a delayed manner up to 55 h.
Co-reporter:Hongwei Huang, Xiaowei Li, Xu Han, Na Tian, Yihe Zhang and Tierui Zhang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 5) pp:3673-3679
Publication Date(Web):15 Dec 2014
DOI:10.1039/C4CP04842C
We, for the first time, demonstrate band-gap-broadening as a new approach to remarkably enhance the photocatalytic activity of Br− substituted BiOI photocatalysts, which were fabricated via a facile chemical precipitation route. The successful incorporation of Br− ions into the crystal lattice of BiOI was confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). The photocatalytic experiments demonstrated that all of the Br–BiOI samples exhibited highly improved photocatalytic performances pertaining to rhodamine B (RhB) and phenol degradation under visible light (λ > 420 nm). The active species trapping and electron spin resonance (ESR) experiments also suggested that more superoxide radicals (˙O2−), serving as the main active species, were generated over Br–BiOI than pristine BiOI in the photooxidation process. Based on the results from experiments and theoretical calculations, the enhancement of photocatalytic activity should be attributed to the lowered valence band (VB) potential and enlarged band gap induced by the Br− replacement, which greatly facilitated the high separation of photoinduced electron–hole pairs, as verified by the photoluminescence (PL) experiments, electrochemical impedance spectra (EIS) and Bode-phase spectra. This work sheds light on a new method to improve the photocatalytic performance of photocatalysts.
We disclose the fabrication of a mediator-free direct Z-scheme photocatalyst system BiVO4/g-C3N4 using a mixed-calcination method based on the more reliable interfacial interaction. The facet coupling occurred between the g-C3N4 (002) and BiVO4 (121), and it was revealed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). The crystal structure and optical properties of the as-prepared samples have also been characterized by Fourier-transform infrared (FTIR), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra (DRS) in details. The photocatalytic experiments indicated that the BiVO4/g-C3N4 composite photocatalysts display a significantly enhanced photocatalytic activity pertaining to RhB degradation and photocurrent generation (PC) compared to the pristine BiVO4 and g-C3N4. This remarkably improved photocatalytic performance should be attributed to the fabrication of a direct Z-scheme system of BiVO4/g-C3N4, which can result in a more efficient separation of photoinduced charge carriers than band–band transfer, thus endowing it with the much more powerful oxidation and reduction capability, as confirmed by the photoluminescence (PL) spectra and electrochemical impedance spectra (EIS). The Z-scheme mechanism of BiVO4/g-C3N4 heterostructure was verified by a series of combined techniques, including the active species trapping experiments, NBT transformation and terephthalic acid photoluminescence probing technique (TA-PL) over BiVO4/g-C3N4 composites and the pristine samples. The present work not only furthered the understanding of mediator-free Z-scheme photocatalysis, but also shed new light on the design of heterostructural photocatalysts with high-performance.
Co-reporter:Hongwei Huang, Liyuan Liu, Yihe Zhang and Na Tian
RSC Advances 2015 vol. 5(Issue 2) pp:1161-1167
Publication Date(Web):25 Nov 2014
DOI:10.1039/C4RA12916D
A novel BiIO4/BiVO4 heterojunction photocatalyst has been successfully developed by a facile hydrothermal route for the first time. X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra (DRS) were utilized to characterize the crystal structures, morphologies and optical properties of the as-prepared products. Under visible light irradiation (λ > 420 nm), the BiIO4/BiVO4 composite exhibits much better photoelectrochemical performance for rhodamine B (RhB) degradation and photocurrent (PC) generation compared to pure BiIO4 and BiVO4. This significant enhancement on visible-light-driven photocatalytic activity should be ascribed to the formation of the BiIO4/BiVO4 heterojunction, which can result in the high separation and transfer efficiency of photogenerated charge carriers. It was verified by electrochemical impedance spectra (EIS). The active species trapping experiment demonstrated that h+ play a critical role during the photocatalytic process, which is consistent with the supposed photocatalytic mechanism.
Co-reporter:Hongwei Huang, Ke Xiao, Na Tian, Yuxi Guo and Yihe Zhang
RSC Advances 2015 vol. 5(Issue 99) pp:81078-81086
Publication Date(Web):08 Sep 2015
DOI:10.1039/C5RA14405A
Plasmon induced Au nanoparticle and surface oxidation induced co-decorated BiOIO3 heterostructured nanocomposites have been developed via a facile in situ photosynthesis route. The structural and optical properties of the as-prepared photocatalysts were systematically characterized by XRD, XPS, TEM, SEM, UV-Vis DRS and PL. Fascinatingly, the introduction of Au nanoparticles induced not only an enhanced photoabsorption in the visible region, but also the microstructural variation of BiOIO3. The oxidative effect of HAuCl4 resulted in the formation of Bi4+/Bi5+, which led to the increased specific surface area of the products. The photocatalysis and photoelectrochemical properties of the samples were investigated by monitoring the photodecomposition of Rhodamine B (RhB) and photocurrent generation under UV-visible light illumination. The results revealed that Au@BiOIO3 presents drastically enhanced photoreactivity compared with the pristine BiOIO3. The highly improved photochemical properties are ascribed to the synergic contribution of the highly promoted generation and separation of charge carriers induced by the surface plasmon resonance (SPR) effect of Au particles, surface chemical state change, as well as the significantly high surface area that provides more reactive sites. These results are corroborated by the electrochemical impedance spectra (EIS), bode-phase spectra, PL spectra, active trapping and DMPO-assisted ESR measurements. This study not only provides evidence for the feasibility of metallic Au as a SPR co-catalyst of bismuth-based materials, but also furnishes new insights into the multiple effects for enhancing the photochemical properties.
Co-reporter:Kun Nie, Qi An, Shengyang Tao, Zepeng Zhang, Xinglong Luan, Qian Zhang and Yihe Zhang
RSC Advances 2015 vol. 5(Issue 71) pp:57389-57394
Publication Date(Web):17 Jun 2015
DOI:10.1039/C5RA07647A
Photothermal materials prepared from graphene and Au nanoparticles have received increasing attentions in various fields ranging from smart devices to advanced medical therapies. In this report, we studied the photothermal transition effects of LbL AuNS/rGO (AuNS: Au nanosheets) films under laser irradiation at 940 nm and comparisons were made with the film of rGO or AuNSs, wherein a single type of photothermal effective species exists. The results indicate that the hybrid LbL AuNS/rGO films displayed enhanced photothermal effects compared with the rGO or AuNSs films. The photothermal performance of the hybrid AuNS/rGO films deteriorated over repeated use or long-term laser irradiation, but the ultimate performance after irradiation was still better than that of the rGO or AuNS films. The hybrid film was able to load the model drug methylene blue (MB), and release MB 4 times faster with NIR irradiation than without, suggesting potential application in the combined chemical and thermal therapies. Thus, the hybrid film of AuNS/rGO is recommended when short-term or few-cycle photothermal applications are required. In comparison, rGO multilayered film better suits long-term or repeated photothermal applications, wherein stable photothermal performance is required.
•AgIO3 as a novel photocatalyst was synthesized by a facile hydrothermal method.•It exhibits excellent photocatalytic activity both under UV and visible light.•The high photocatalytic activity is attributed to the non-centrosymmetric structure.•AgIO3 also shows high stability resistant to photocorrosion.AgIO3 as a novel photocatalyst was prepared via a facile hydrothermal route. The microstructure, electronic structure, optical and nonlinear optical (NLO) properties of AgIO3 were investigated by a series of experimental and theoretical methods, including X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), Brunauer–Emmett–Teller (BET), UV–vis diffuse reflectance spectra (DRS), second harmonic generation (SHG) measurements and the first principle calculation. The results revealed that AgIO3 exhibits a strong SHG response and excellent photocatalytic performance with high stability under both UV and visible light irradiation. The advantages of this material, such as large polarizability resulted from the NCS structure, polar IO3− anion and layered structure should be responsible for the high photocatalytic activity of AgIO3. The present work may shed new light on the design of multifunctional materials.
Co-reporter:Xuelian Yu, Jingjing Liu, Aziz Genç, Maria Ibáñez, Zhishan Luo, Alexey Shavel, Jordi Arbiol, Guangjin Zhang, Yihe Zhang, and Andreu Cabot
Langmuir 2015 Volume 31(Issue 38) pp:10555-10561
Publication Date(Web):September 7, 2015
DOI:10.1021/acs.langmuir.5b02490
A cation exchange-based route was used to produce Cu2ZnSnS4 (CZTS)–Ag2S nanoparticles with controlled composition. We report a detailed study of the formation of such CZTS–Ag2S nanoheterostructures and of their photocatalytic properties. When compared to pure CZTS, the use of nanoscale p–n heterostructures as light absorbers for photocatalytic water splitting provides superior photocurrents. We associate this experimental fact to a higher separation efficiency of the photogenerated electron–hole pairs. We believe this and other type-II nanoheterostructures will open the door to the use of CZTS, with excellent light absorption properties and made of abundant and environmental friendly elements, to the field of photocatalysis.
Co-reporter:Deyang Zhang, Yihe Zhang, Yongsong Luo, Paul K. Chu
Nano Energy 2015 Volume 13() pp:47-57
Publication Date(Web):April 2015
DOI:10.1016/j.nanoen.2015.01.047
•Highly porous honeycomb-like manganese oxide@carbon fibers core–shell materials are introduced into the anode of SCs.•Excellent electrochemical performance and flexible mechanical properties are obtained.•The simple and economical approach enables the design of hybrid electrode architectures for flexible energy storage devices.Core–shell electrodes composed of highly porous honeycomb manganese oxide@carbon fibers (HMO@CFs) are synthesized by a facile hydrothermal approach involving an in situ redox replacement reaction between potassium permanganate (KMnO4) and carbon fibers. In this reaction, the carbon fibers serve as not only a sacrificial reductant, but also the substrate. The porous HMO@CFs core–shell nanocables deliver remarkable electrochemical performance with a high capacitance (295.24 F g−1 at 100 mA g−1), high good rate capability, and superior cycling stability (about 96.4% specific capacitance retained after 3000 cycles). The maximum energy density of 22.2 W h kg−1 (at a power density of 400 W kg−1) and power density of 12,000 W kg−1 (at an energy density of 10 W h kg−1) can be achieved at an operating voltage of 1.6 V. The fabrication method is simple, cost-effective, and readily scalable thereby having large commercial potential.Core/shell electrodes composed of highly porous honeycomb manganese oxide@carbon fibers (HMO@CFs) are synthesized hydrothermally using an in situ redox replacement reaction between potassium permanganate (KMnO4) and carbon fibers. The materials deliver excellent performance in flexible supercapacitors boasting high specific capacity and stability.
Co-reporter:Ying He, Yihe Zhang, Hongwei Huang, Xiaowei Li, Na Tian, Yuxi Guo, Yi Luo
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 467() pp:195-200
Publication Date(Web):20 February 2015
DOI:10.1016/j.colsurfa.2014.11.007
•BaBiO2Br was first explored as a novel photocatalyst.•BaBiO2Br has been successfully synthesized by a solid state reaction.•We systematically synthesized BaBiO2Br in different temperature.•Pure BaBiO2Br can only be obtained at 800 °C and 900 °C.•BaBiO2Br calcinated at 700 °C exhibited the highest photocatalytic activity.A novel Bi-based layered photocatalyst BaBiO2Br was successfully prepared by a solid-state reaction. The as-prepared samples were characterized by XRD, SEM, DRS, PL and FT-IR. The calcination temperature was found to play an important role in controlling synthesis of BaBiO2Br, and pure BaBiO2Br can only be obtained at 800–900 °C. BaBiO2Br with an indirect optical band-gap of 2.93 eV possess photoabsorption ability in both ultraviolet (UV) and visible light regions. The valence band (VB) were mainly occupied by O 2p and Br 4p orbitals, and the conduction band (CB) was composed of Bi 6p orbital. The photodecomposition of rhodamine-B (RhB) experiments revealed that BaBiO2Br can be used as an effective photocatalyst under UV light and visible light irradiation (λ > 400 nm). The sample calcinated at 700 °C exhibited the highest photocatalytic activity among the obtained BaBiO2Br samples, which may be due to the formation of a heterostructure. Among the obtained pure BaBiO2Br, the sample calcinated at 900 °C possesses higher photocatalytic activity than that prepared at 800 °C for its more surface hydroxyl groups at 900 °C.A novel Bi-based layered BaBiO2Br was successfully prepared by a solid state reaction at different temperature. BaBiO2Br has an indirect-transition optical band-gap of 2.93 eV and showed photodegradation of RhB under UV light and visible light irradiation.
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 467() pp:188-194
Publication Date(Web):20 February 2015
DOI:10.1016/j.colsurfa.2014.11.049
•g-C3N4/Ag2CO3 composites were synthesized by a facile in situ precipitation route.•The 1:12 g-C3N4/Ag2CO3 sample shows the most improved photocatalytic performance.•The enhanced photocatalytic activity was attributed to a heterojunction mechanism.•The active species h+ and OH were detected by species trapping experiment.Novel g-C3N4/Ag2CO3 organic–inorganic hybrid photocatalysts have been prepared by a facile in situ precipitation route. The crystal structure and optical property of the as-prepared samples have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and diffuse reflection spectroscopy (DRS). The photocatalytic experiments indicated that the as-prepared g-C3N4/Ag2CO3 photocatalyst exhibited significantly enhanced photocatalytic activity than the pure g-C3N4 and Ag2CO3 samples toward degrading methyl orange (MO) under visible light irradiation (λ > 420 nm). A possible photocatalytic mechanism was proposed based on the photoluminescence (PL) spectra, photocurrent spectra and a series of radical trapping experiments. The remarkably improved photocatalytic performance should be ascribed to the heterostructure between Ag2CO3 and g-C3N4, which greatly promoted the photoinduced charge transfer and inhibited the recombination of electrons and holes.The efficient charge transfer at the interface of g-C3N4/Ag2CO3 heterojunction leads to an effective photoexcited electron–hole separation and promote the photocatalytic activity.
The Journal of Physical Chemistry C 2015 Volume 119(Issue 30) pp:17156-17165
Publication Date(Web):July 13, 2015
DOI:10.1021/acs.jpcc.5b03707
We developed for the first time an in situ co-crystallization route for fabrication of a heterojunctional photocatalyst g-C3N4/Bi5O7I by adopting melamine and BiOI as coprecursors. This synthetic method enables intimate interfacial interaction with chemical bonding between g-C3N4 and Bi5O7I, which is beneficial for charge transfer at the interface. The photocatalysis properties of g-C3N4/Bi5O7I composites were studied by photodegradation of Rhodamine B (RhB) and phenol and generation of transient photocurrent with illumination of visible-light (λ > 420 nm), The results revealed that the g-C3N4/Bi5O7I composite shows enhanced photocatalytic reactivity compared to the pristine g-C3N4 and Bi5O7I samples. Investigations on the behaviors of charge carriers via electrochemical impedance spectra (EIS) and photoluminescence (PL) spectra suggests that the g-C3N4/Bi5O7I heterojunctional structure constructed of the in situ co-thermolysis approach is responsible for the efficient separation and transfer of photogenerated electrons (e–) and holes (h+), thus giving rise to the higher photocatalytic activity. The present work opens a new avenue for manipulation of high-performance semiconductor heterojunction for photocatalytic and photoelectrochemical application.
The Journal of Physical Chemistry C 2015 Volume 119(Issue 38) pp:21882-21888
Publication Date(Web):August 26, 2015
DOI:10.1021/acs.jpcc.5b06199
We report the synthesis and photocatalytic and magnetic characterization of colloidal nanoheterostructures formed by combining a Pt-based magnetic metal alloy (PtCo, PtNi) with Cu2ZnSnS4 (CZTS). While CZTS is one of the main candidate materials for solar energy conversion, the introduction of a Pt-based alloy on its surface strongly influences its chemical and electronic properties, ultimately determining its functionality. In this regard, up to a 15-fold increase of the photocatalytic hydrogen evolution activity was obtained with CZTS–PtCo when compared with CZTS. Furthermore, two times higher hydrogen evolution rates were obtained for CZTS–PtCo when compared with CZTS–Pt, in spite of the lower precious metal loading of the former. Besides, the magnetic properties of the PtCo nanoparticles attached to the CZTS nanocrystals were retained in the heterostructures, which could facilitate catalyst purification and recovery for its posterior recycling and/or reutilization.
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 481() pp:493-499
Publication Date(Web):20 September 2015
DOI:10.1016/j.colsurfa.2015.05.047
•Amine containing SiO2 foams are prepared for specific organic treatment.•Secondary amine modified foams show excellent COD removal capacity.•Adsorption behavior fit the pseudo-second-order dynamic and Langmuir adsorption models well.•Adsorption bases on the attraction between amine groups on foam and the negative organic pollutants.Secondary and primary amines containing silica foams (F–SiO2) were prepared by using silane coupling agents, (3-aminopropyl) triethoxysilane (KH-550) and bis(3-triethoxysilicyl propyl)-amine (KH-270), as modifiers. Not only Brunauer–Emmett–Tell (BET) surface and pore size of F–SiO2 are greatly reduced after modification, but also increased chemical oxygen demand (COD) removal efficiency to trinitrotoluene (TNT) red water is obtained. Among the series of F–SiO2, the secondary amine modified silica foams possess higher COD removal capacity. Controlled experiments indicate the adsorption mainly derives from the attraction of amine groups toward the negative organic pollutants in TNT red water rather than the effect of the large BET surface and hydroxyl groups on the surface of F–SiO2. The adsorption model studies show the pseudo-second-order dynamic adsorption model and Langmuir isotherm model well fit the experimental data. The prepared amine-modified F–SiO2 is an efficient adsorbents of organic pollutants in TNT red water.
Co-reporter:Zilin Meng, Xiaowei Li, Fengzhu Lv, Qian Zhang, Paul K. Chu, Yihe Zhang
Colloids and Surfaces B: Biointerfaces 2015 Volume 135() pp:339-345
Publication Date(Web):1 November 2015
DOI:10.1016/j.colsurfb.2015.07.069
•Aspirin was firstly intercalated into Zn–Al-layered double hydroxides by two methods and released in two buffered solutions: phosphate and borate buffered saline.•By molecular simulation, the firstly illuminate the different arrangement of molecules in LDH interlayers influenced by different preparation.•In the release process, the first time explain the anion exchange process by bonding energy calculated by Material Studio.•Experimental phenomenon that the structure of LDH was destroyed after release in phosphate buffered saline is first reported and analyzed.Aspirin or acetylsalicylic acid (AA), a non-steroidal anti-inflammatory drug, is intercalated into Zn–Al-layered double hydroxides (ZnAl-LDHs) by co-precipitation and reconstruction methods. The composition, structure, and morphology of the intercalated products as well as their release behavior are determined experimentally and theoretically by Material Studio 5.5. Experimental results disclose the strong interaction between the LDHs sheets and AA in the intercalated ZnAl-LDHs produced by co-precipitation and slow release of AA from the intercalated ZnAl-LDHs in both phosphate buffered saline (PBS) and borate buffered saline (BBS) solutions. The percentage of AA released from the ZnAl-LDHs prepared by both methods in PBS (96.87% and 98.12%) are much more than those in BBS (68.59% and 81.22%) implying that both H4BO4− and H2PO4− can exchange with AA in the ZnAl-LDHs. After AA is released to PBS, ZnAl-LDHs break into small pieces. The experimental results are explained theoretically based on the calculation of the bonding energy between the anions and LDHs sheets as well as the AlO bond length change in the LDHs sheets.
Journal of Materials Chemistry A 2014 vol. 2(Issue 40) pp:8501-8506
Publication Date(Web):01 Aug 2014
DOI:10.1039/C4TC01097C
Recyclable, fast and visible-light responsive polymer-dispersed liquid crystal (PDLC)/graphene oxide (GO) nanocomposite films were successfully fabricated by a combination of solution casting and mechanical stretching. In the PDLC/GO nanocomposite films, one low-molecular-weight nematic LC (5CB) formed a separated phase and GO-dispersed polyvinyl alcohol (PVA) was used as the film matrix. Upon irradiation with visible light, PDLC/GO nanocomposite films showed photomechanical response, bending toward the light source along the stretching direction. Here, GO functioned as the light absorbent and nanoscale heat source to thermally induce a phase transition with 5CB from homogeneous alignment to an isotropic phase. Thus, volume contraction occurred on the surface area of the nanocomposite films due to the photothermal effect of GO, whereas little change took place in the opposite area, resulting in the visible light-induced photomechanical response in a bimetal-like mode. These PDLC/GO nanocomposite films can be potentially applied in soft actuators and micro-optomechanical systems with visible light as the energy source.
Co-reporter:Zhentao Cui, Shuguang Wang, Yihe Zhang, Minhua Cao
Journal of Power Sources 2014 Volume 259() pp:138-144
Publication Date(Web):1 August 2014
DOI:10.1016/j.jpowsour.2014.02.084
•N–S co-doped hierarchical porous carbons were prepared by using ionic liquid.•They exhibit high specific surface area.•They exhibit significantly enhanced electrocatalytic activity for ORR.We for the first time demonstrate a simple and green approach to heteroatom (N and S) co-doped hierarchically porous carbons (N–S-HC) with high surface area by using one organic ionic liquid as nitrogen, sulfur and carbon sources and the eutectic salt as templating. The resultant dual-doped N–S-HC catalysts exhibit significantly enhanced electrocatalytic activity, long-term operation stability, and tolerance to crossover effect compared to commercial Pt/C for oxygen reduction reactions (ORR) in alkaline environment. The excellent electrocatalytic performance may be attributed to the synergistic effects, which includes more catalytic sites for ORR provided by N–S heteroatom doping and high electron transfer rate provided by hierarchically porous structure. The DFT calculations reveal that the dual doping of S and N atoms lead to the redistribution of spin and charge densities, which may be responsible for the formation of a large number of carbon atom active sites. This newly developed approach may supply an efficient platform for the synthesis of a series of heteroatom doped carbon materials for fuel cells and other applications.
Nonbonding layer-structured Y(IO3)3 was successfully prepared by a simple hydrothermal route and investigated as a novel photocatalyst for the first time. Its crystal structure was characterized by X-ray diffraction, high-resolution transmission electron microscopy, and scanning electron microscopy. The optical absorption edge and band gap of Y(IO3)3 have been determined by UV–vis diffuse reflectance spectra. Theoretical calculations of the electronic structure of Y(IO3)3 confirmed its direct optical transition property near the absorption edge region, and the orbital components of the conduction band and valence band (VB) were also analyzed. The photocatalytic performance of Y(IO3)3 was evaluated by photooxidative decomposition of rhodamine B under ultraviolet light irradiation. It demonstrated that Y(IO3)3 exhibits highly efficient photocatalytic activity, which is much better than those of commercial TiO2 (P25) and important UV photocatalysts BiOCl and BiIO4. The origin of the excellent photocatalytic performance of Y(IO3)3 was investigated by electron spin resonance and terephthalic acid photoluminescence techniques. The results revealed that the highly strong photooxidation ability that resulted from its very positive VB position should be responsible for the excellent photocatalytic performance.
Ceramics International 2014 Volume 40(Issue 4) pp:5407-5412
Publication Date(Web):May 2014
DOI:10.1016/j.ceramint.2013.10.122
Abstract
Mineral wool fibers (MWF) commonly used in building insulation and decoration are incorporated with cuprous oxide particles at room temperature to inactivate Escherichia coli (E. coli). X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet–visible diffuse reflection absorption spectroscopy (UV–vis/DRS) are employed to characterize the photocatalytic composites and the bactericidal effects are assessed by UV–visible spectrophotometry. Cuprous oxide particles with a size of 100 nm can be immobilized effectively on the surface of the MWF. The MWF improves the optical properties of cuprous oxide and red-shifts the band gap thereby enhancing the utilization efficiency of visible light. The Cu2O/MWF composites deliver excellent photocatalytic performance in the inactivation of E. coli. After illumination for 24 h, more than 95% of the bacteria are inactivated and the materials are suitable for indoor antibacterial applications.
Co-reporter:Hongwei Huang, Shuobo Wang, Yihe Zhang and Paul K. Chu
RSC Advances 2014 vol. 4(Issue 78) pp:41219-41227
Publication Date(Web):15 Aug 2014
DOI:10.1039/C4RA05708B
Energy-levels well-matched Mg1−xCuxWO4 (0.1 < x < 0.5)/Bi2WO6 heterojunctions with Type II staggered conduction bands and valence bands have been successfully constructed by band gap engineering based on solid-solution design and synthesized by a facile one-step hydrothermal method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV-vis diffuse reflectance spectra (DRS) were utilized to characterize the crystal structures, morphologies and optical properties of the as-prepared products. The as-designed Mg0.7Cu0.3WO4/Bi2WO6 heterojunctions consisting of nanocube and nanoplate structures exhibit much higher visible-light-driven (VLD) photocatalytic activity than the two individual components for the degradation of RhB and photocurrent generation. The photoluminescence (PL) spectra, photoelectrochemical measurement, active-species trapping and quantification experiments all indicated that the fabrication of energy-levels well-matched overlapping band structures can greatly facilitate the separation and easy transfer of photogenerated electrons and holes, thus resulting in remarkably enhanced photocatalytic activity. This work provides a novel strategy for semiconductor heterojunction construction and energy band structure regulation.
The g-C3N4/BiIO4 composite photocatalysts were successfully synthesized using a simple-mixed-calcinations method, and their photocatalytic activities for degradation of rhodamine B (RhB) under visible-light (λ > 420 nm) were investigated for the first time. The crystal structure and optical property of the as-synthesized samples were characterized by XRD, FTIR, SEM, TEM, HRTEM and DRS spectroscopy. The photodegradation experiments indicated that the g-C3N4/BiIO4 composite photocatalyst displays a higher photocatalytic activity than the two individuals, which was also confirmed by the PL spectra and photoelectrochemical experiments. This remarkably improved photocatalytic performance can be attributed to the heterojunction structure of g-C3N4/BiIO4 composites, which possess stronger oxidation and reduction capability, thus resulting in the efficient separation of photoinduced charge carriers as demonstrated in the active species experiments. The present study will be beneficial for the design of high performance photocatalysts.
Co-reporter:Hongwei Huang, Kun Liu, Yinglei Zhang, Kai Chen, Yihe Zhang and Na Tian
RSC Advances 2014 vol. 4(Issue 90) pp:49386-49394
Publication Date(Web):17 Sep 2014
DOI:10.1039/C4RA07533A
Novel 3D hierarchical graphene–BiOI (GR–BiOI) nanoarchitectures have been successfully fabricated via an in situ self-assembly approach for the first time. More attractively, the hierarchical nanoarchitectures can be adjusted by simply controlling the amount of graphene oxide, which determines the improved level of photocatalytic performance. Photochemical measurements reveal that the as-obtained 5% GR–BiOI composite exhibits the most significantly enhanced photocatalytic activities for the degradation of Rhodamine B (RhB) and photocurrent (PC) generation under visible light irradiation (λ > 420 nm). This remarkably improved photocatalytic performance of GR–BiOI could be attributed to the well-established interfacial interaction between graphene and BiOI, which can greatly facilitate the separation and easy transfer of photogenerated electrons and holes to generate abundant ˙O2− and ˙OH active species with powerful oxidability. This was verified by the photoluminescence (PL) spectra, electrochemical impedance spectra (EIS), active species trapping, and ˙O2− and ˙OH quantification experiments. Our work provides a new strategy for the construction of hierarchical nanoarchitectures of high-performance composite photocatalysts and paves an alternative way to the design and synthesis of graphene-based composites for special applications.
An electrochemical immunosensor for quantitative detection of α-fetoprotein (AFP) in human serum was developed using graphene sheets (GS) and thionine (TH) as electrode materials and mesoporous silica nanoparticles (MSNs) loaded with ferroferric oxide (Fe3O4) nanoparticles and horseradish peroxidase (HRP) as labels for signal amplification. In this study, the compound of GS and TH (GS–TH) was used as a substrate for promoting electron transfer and immobilization of primary antibody of AFP (Ab1). MSNs were used as a carrier for immobilization of secondary antibody of AFP (Ab2), Fe3O4, and HRP. The synergistic effect occurred between Fe3O4 and HRP and greatly improved the sensitivity of the immunosensor. This method could detect AFP over a wide concentration range from 0.01 to 25 ng ml−1 with a detection limit of 4 pg ml−1. This strategy may find wide potential application in clinical analysis or detection of other tumor markers.
Co-reporter:Yihe Zhang, Keke Cheng, Fengzhu Lv, Hongwei Huang, Bin Fei, Ying He, Zhengfang Ye, Bo Shen
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 452() pp:103-108
Publication Date(Web):20 June 2014
DOI:10.1016/j.colsurfa.2014.03.086
•Pure TiO2, Fe-N-doped TiO2, Fe-S-doped TiO2 and Fe-N-S-doped TiO2 were prepared.•The multi-doped TiO2 have been prepared by the new route from the Fe3+ doped PTC.•The absorption edge of Fe-N-S-doped TiO2 shifted to 535 nm.•The multi-doped TiO2 shown higher photocatalytic activity in degradation of TNT.•Fe-N-S-doped TiO2 exhibited the best photocatalytic activity.Fe-N-doped TiO2, Fe-S-doped TiO2 and Fe-N-S-doped TiO2 were prepared with Fe doping peroxotitanium complex (Fe-PTC) as precursor in aqueous solution by a low-temperature process. The structure and properties of catalysts were characterized by XRD, FT-IR, XPS, TEM and UV–Vis respectively. Fe-N-doped TiO2, Fe-S-doped TiO2 and Fe-N-S-doped TiO2 all belong to anatase phase. The UV–Vis spectra of doped TiO2 exhibited a red shift to 535 nm and stronger absorption than that of pure TiO2 in visible region. The pure TiO2 displays bullet-like morphology with widths of about 20 nm and Fe-N-S-doped TiO2 consisted of irregular particles with diameters about 5–10 nm. The doped samples all exhibited higher photocatalytic activity in the degradation of 2,4,6-trinitotoluene (TNT) in red water compared to pure TiO2. Fe-N-S-doped TiO2 presented the highest photocatalytic activity and degraded about 91.5% 2,4,6-trinitotoluene within 12 h under visible light irradiation. Structural characterization and property analysis results revealed that the co-doping of Fe-N, Fe-S and Fe-N-S remarkably altered the crystal specific surface area, microstructure, as well as the photocatalytic activity.Pure TiO2, Fe-N-doped TiO2, Fe-S-doped TiO2 and Fe-N-S-doped TiO2 were successfully prepared. The multi-doped TiO2 shown photodegradation of TNT in red water under visible-light irradiation.
Co-reporter:Ying He, Yihe Zhang, Hongwei Huang, Na Tian, Yuxi Guo, Yi Luo
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 462() pp:131-136
Publication Date(Web):20 November 2014
DOI:10.1016/j.colsurfa.2014.07.034
•Bi4NbO8Br was explored as a novel photocatalyst with visible light response.•Bi4NbO8Br has been successfully synthesized by a solid state reaction.•We systematically synthesized Bi4NbO8Br in different temperatures.•Pure Bi4NbO8Br can only be obtained at 700 °C, 750 °C and 800 °C.•Bi4NbO8Br calcinated at 750 °C exhibited the highest photocatalytic activity.A novel visible-light-driven Bi-based layered photocatalyst Bi4NbO8Br was successfully prepared by a solid state reaction. The calcination temperature was found to play an important role in controlling synthesis of Bi4NbO8Br, and pure Bi4NbO8Br can only be obtained at 700 °C–800 °C. The as-prepared samples were characterized by XRD, SEM, DRS and PL. Bi4NbO8Br has an indirect-transition optical band-gap of 2.34 eV, and the ECB and EVB are estimated to be 0.63 eV and 2.97 eV, respectively. The photocatalytic activities of the samples were determined by decomposition of rhodamine-B (RhB) in aqueous solution under visible light illumination. The results revealed that the sample calcinated at 750 °C exhibited the highest photocatalytic activity among the pure Bi4NbO8Br samples. The sample calcinated at 850 °C, composed of BiNbO4 and Bi4NbO8Br, showed higher photocatalytic activity than that calcinated at 750 °C, which may be due to the formation of heterostructure.Bi4NbO8Br was successfully prepared by a solid state reaction at different temperatures. Bi4NbO8Br has an indirect-transition optical band-gap of 2.34 eV and showed photodegradation of RhB under visible-light irradiation.
Co-reporter:Kun Tong, Yihe Zhang, Dan Fu, Xianghai Meng, Qi An, Paul K. Chu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 447() pp:120-130
Publication Date(Web):5 April 2014
DOI:10.1016/j.colsurfa.2014.01.062
•Lignite activated coke was used to adsorb organic pollutants from super heavy oil wastewater.•The adsorption fitted well to pseudo-second-order kinetics and Freundlich model.•Adsorption was a endothermic and the randomness increases chemical process.•The removed organic compounds are of high molecular weight and of complicated structures.•LAC was able to remove COD, oils, Mg2+, Ca2+, total salts and was an economic, effective absorbent.Extraction of organic pollutants from super heavy oil wastewater (SHOW) by lignite activated coke (LAC) is investigated. The factors studied include the exposure time, temperature, and different pollutant concentrations in the wastewater. The equilibrium adsorption data are analyzed by the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) isotherms. The best match is obtained by the Freundlich isotherm and a chemical mechanism is suggested based on the D–R model. The adsorption kinetics follows the pseudo second order model and the mass transfer model suggests that external and intra-particle diffusion influences the adsorption process. Thermodynamics studies show that adsorption of organic materials is spontaneous at high temperature (303 and 313 K) but not so at lower temperature (293 K) and reveals an endothermic process and increase in randomness during adsorption. The pilot dynamic adsorption test indicates that LAC can remove not only organic pollutants such as COD, NH3-N, oils, but also inorganic pollutants such as Mg2+, Ca2+, and salts.
Co-reporter:Hongwei Huang ; Kun Liu ; Kai Chen ; Yinglei Zhang ; Yihe Zhang ;Shichao Wang
The Journal of Physical Chemistry C 2014 Volume 118(Issue 26) pp:14379-14387
Publication Date(Web):June 17, 2014
DOI:10.1021/jp503025b
The novel Ce and F codoped Bi2WO6 samples have been successfully obtained by a facile one-step hydrothermal reaction for the first time. They were characterized by X-ray diffraction patterns (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectra (DRS) and photoluminescence (PL) spectra. The presence of Ce3+, Ce4+, and F– dopants in Bi2WO6 was confirmed by XPS. The change of microstructure and optical band gap has also been observed after the doping of Ce and F. Under visible light, the as-synthesized plate-like F–Ce–Bi2WO6 sample exhibits a much better visible-light-responsive photocatalytic performance than pure Bi2WO6 for the degradation of RhB and photocurrent (PC) generation. The mechanism of high photcatalytic activity was also suggested on the basis of the PL spectra, electrochemical impedance spectra (EIS), and active species trapping measurements. The results indicated that the synergistic effect of the Ce and F dopants is responsible for the efficient separation and migration of photoinduced charge carriers, thus resulting in the remarkably improved photocatalytic activity.
Co-reporter:Wangshu Tong ; Yihe Zhang ; Li Yu ; Xinglong Luan ; Qi An ; Qian Zhang ; Fengzhu Lv ; Paul K. Chu ; Bo Shen ;Zhilei Zhang
The Journal of Physical Chemistry C 2014 Volume 118(Issue 20) pp:10567-10573
Publication Date(Web):May 1, 2014
DOI:10.1021/jp411828e
Carbon–polymer nanocomposites with good dielectric properties have potential applications in the electronic and electrical industry because of their good mechanical properties and low cost. The morphology, structure, dielectric properties, and mechanical strength of reduced-graphene oxide nanosheet/poly(vinylidene fluoride-co-hexafluoropropylene) nanocomposites (rGO/PVDF-HFP) were investigated. The rGO nanosheets were well dispersed and strongly oriented in the matrix, thanks to the unique spin-assistant preparation process. A dielectric constant of 54 (100 Hz) which was four times higher than that of pure PVDF-HFP was obtained when the concentration of rGO was 0.7 vol % and the dielectric loss was as low as 0.27. The good dielectric performance of the nanocomposites was attributed to the homogeneous dispersion and good alignment of rGO. The shear force provided by spin-coating, the thickness decreasing process, and thickness control were assumed to be key factors in the alignment of rGO nanosheets in the nanocomposite films. At the same time, the aligned rGO sheets increased the percolation threshold of the composite which shed light on the mechanism for obtaining low loss materials.
The Journal of Physical Chemistry C 2014 Volume 118(Issue 35) pp:20357-20362
Publication Date(Web):August 11, 2014
DOI:10.1021/jp505225z
Constructing stable and reliable interfaces around pseudo two-dimensional clay materials is a key process in achieving advanced and reliable performance of related composite materials. However, the effective surface modification of pseudo two-dimensional clay has been a challenging research topic. In this study, we have developed an effective and facile method for the interfacial modification of magnetic montmorillonite (MMT) nanocomposite by using covalent layer-by-layer (LbL) assembly. The method involves conventional LbL assembly around the magnetic MMT followed by infiltration of a bifunctional photoactive small molecule and then covalent cross-linking of the LbL multilayers upon UV irradiation. After covalent LbL modification, the nanocomposite presented ample organic species around its interfaces and displayed stable organic interfaces even in extreme solution conditions such as in basic (pH =14) solutions. The covalent cross-linking of the multilayers proved to be indispensable in keeping the LbL multilayers stable around the MMT composites. After modification, the composite particles kept their magnetic properties. In addition, the release profile of the composite particles for methyl blue indicated that the composite particles preserved the capacity to carry loads and release them in retarded speed. This method will potentially integrate the merits of LbL multilayers with MMT to achieve advanced functional materials.
Journal of Sol-Gel Science and Technology 2014 Volume 69( Issue 1) pp:26-32
Publication Date(Web):2014 January
DOI:10.1007/s10971-013-3180-9
Surfactant-intercalated MgFe-layered double hydroxides (MgFe-LDHs) were successfully synthesized via one-step self-assembly of the surfactants (sodium dodecyl sulfate, 1-hexadecane sulfate, and sodium dodecyl benzene sulfonate) and the LDH precursors without avoiding dissolved CO32−. As a control, p-toluene sulfonic acid was used to further study the functions of surfactants. The detailed characterization of the surfactant intercalated MgFe-LDHs and their intermediates confirm that the basal spacing changes of the formed LDHs derive from the release of surfactants out of LDH interlayers or the adsorption of surfactants from the solution in the reaction. Besides, the Mg/Fe ratio of the LDH sheets increases with the reaction and the corresponding ionic exchange capacity (IEC) of the MgFe-LDHs decreases. The final surfactant intercalated MgFe-LDH particles are the mixture of MgFe-LDH sheets with different composition and IEC, which can be the basic principle of LDH preparation for different applications. Also the Mg/Fe ratio of the surfactant intercalated MgFe-LDHs decreases with the increase of molecular length of surfactants used.
The novel adsorbent Cu-impregnated activated coke (CAC) has been successfully prepared using a Cu(NO3)2 solution impregnated activated coke (AC). The optimum preparation conditions of CAC are the concentration of Cu(NO3)2 of 0.1 mol/L, pH of 6, loading time of 4 h, and loading temperature of 333 K. The characterizations of CAC are analyzed by N2 adsorption, X-ray diffraction, scanning electron microscope, and energy dispersive X-ray spectroscopy. Also the adsorption behavior of CAC to organic materials in TNT red water is studied. The adsorption data are simulated by Freundlich isotherm and Langmuir isotherm. Below 333 K Freundlich isotherm is more suitable, while Langmuir isotherm model is more fitted when the temperature is higher than 333 K. The adsorption kinetics follows a pseudo second-order model, and thermodynamic analysis indicates an endothermic and spontaneous adsorption processes, and the process appears to be controlled by the chemisorption process. Chemical oxygen demand of 85.34 % can be removed as CAC prepared under optimized conditions is used as absorbent. In summary, CAC has excellent absorption characteristics and can be used in the removal of organic materials from TNT red water.
Co-reporter:Jiwu Shang, Yihe Zhang, Li Yu, Xinglong Luan, Bo Shen, Zhilei Zhang, Fengzhu Lv and Paul K. Chu
Journal of Materials Chemistry A 2013 vol. 1(Issue 3) pp:884-890
Publication Date(Web):26 Oct 2012
DOI:10.1039/C2TA00602B
Graphene–polyvinylidene fluoride hybrid films (GPNs–PVDF) with a polyaniline (PANI) interlayer are fabricated by a facile and effective process. The morphology of the graphene–polyaniline nanoflakes (GPNs) is examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and the interaction between graphene and PANI is investigated by Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The GPNs have a layered structure resembling a cake with the graphene sheets sandwiched between the PANI layers. The GPNs have a uniform morphology which can be controlled by adjusting the ratio of PANI to graphene. The PANI inter-layer plays an active role in the dielectric properties of the GPNs–PVDF composites which have low dielectric loss, high breakdown field, and large energy density. The enhanced dielectric performance originates from the insulating PANI layer which not only ensures good dispersion of graphene sheets in the PVDF but also acts as an inter-particle barrier to prevent direct contact with the graphene sheets.
Co-reporter:Yuxia Yin, Yihe Zhang, Zhichao Zhen, Paul K. Chu, Fengzhu Lv, Junhui Ji
Composites Science and Technology 2013 Volume 85() pp:131-135
Publication Date(Web):21 August 2013
DOI:10.1016/j.compscitech.2013.06.002
A modified flame-retardant boron mud (FRBM) developed from raw boron mud (BM) was incorporated into polypropylene (PP) with organic modified montmorillonite (OMMT) to obtain PP/FRBM and PP/FRBM/OMMT blends. The BM and FRBM were analyzed by XRD, TGA and XRF. The flame retarding characteristics of the composites were studied by LOI and rate-of-burning (RB) tests. The morphology of the charred residues was examined by SEM. XRD reveals that FRBM contains forsterite, cordierite, muscovite, and brucite. The TGA thermograms indicate that FRBM begins to lose weight sharply at 350 °C and FRBM/OMMT at 300 °C. XRF reveals the levels of elements in BM vary at different temperature. The LOI and RB test show that a larger FRBM content gives good flame resistance and the combination of OMMT and FRBM delivers better results. The SEM pictures illustrate that the PP/FRBM/OMMT residues make a thicker charred layer than the PP/FRBM residues.
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2013 Volume 419() pp:46-52
Publication Date(Web):20 February 2013
DOI:10.1016/j.colsurfa.2012.11.047
Calcium chloride (CaCl2) is used together with cationic poly (dimethylamine-co-epichlorohydrin) (P-DcE) and cationic polyacrylamine (CPAM) to demulsify super heavy oil wastewater. A new reverse emulsion breaker (REB) with the optimal ratio of P-DcE to CaCl2 to CPAM of 20:600:1.2 (m/m) can remove 98.04% mineral oil and 94.48% COD. Compared to P-DcE used alone and P-DcE supplemented with concentrated sulfuric acid to enhance demulsification, the advantages of the REB are high removal rates for mineral oil and COD, low cost, and environmental friendliness. GC–MS indicates that the REB can remove more organic compounds such as mineral oils than other agents and most of the residues are oilfield chemicals such as corrosion inhibitors, scale inhibitors, biocides, and demulsifiers. The REB, which exhibits good efficiency in anaerobic digestion and synergistic demulsification of SHOW arising from CaCl2, is efficient, safe, and economical.Highlights► CaCl2 has a good performance in synergistic demulsification of super heavy oil wastewater. ► A new demulsifier REB is combined with P-DcE,CaCl2 and CPAM. ► REB can remove more mineral oil, COD and organic compounds than two traditional demulsifiers. ► The REB effluent has low BOD/COD and delivers good performance in anaerobic digestion. ► REB is an efficient, safe and economical demulsifier of super heavy oil wastewater.
Journal of Materials Science 2013 Volume 48( Issue 16) pp:5437-5446
Publication Date(Web):2013 August
DOI:10.1007/s10853-013-7337-2
Surfactant-intercalated Zn and Al layered double hydroxides (ZnAl-LDHs) were synthesized via spontaneous self-assembly of the surfactants (sodium dodecyl sulfate and sodium dodecyl benzene sulfonate) and the LDH salt precursors. To understand the function of the surfactants in the synthesis, the surfactant-modified ZnAl-LDHs and their intermediates before aging were characterized via X-ray diffraction, Fourier transform infrared spectroscopy, Field emission scanning electron microscopy, and thermogravimetric analysis. In addition, fluorescence spectroscopy was used to in situ trace the microenvironmental variations of the reactants in the synthesis. It was found that the anionic surfactants can interact with the LDH precursors to form cooperative micellar assemblies, which increase the concentration of cationic counter ions around the micelles leading to enhanced growth of the LDH sheets along their lamellar surface direction and the stacking of LDH sheets into nanoparticles as the surfactant possesses longer molecular length. Because of the hydrophobicity of the intermediate sheets coated with surfactants, the reaction between the dissolved CO32− and the LDH intermediate sheets can be greatly reduced, and thus no strict N2 protection was necessary in this method. This mechanistic understanding of the effects of the surfactants on the formation of LDHs is critical in successful synthesis of organic-intercalated LDHs in complicated system by void the interruption of competitive ions.
Co-reporter:Yihe Zhang, Chunxiao Yu, Paul K. Chu, Fengzhu Lv, Changan Zhang, Junhui Ji, Rui Zhang, Heli Wang
Materials Chemistry and Physics 2012 Volume 133(2–3) pp:845-849
Publication Date(Web):16 April 2012
DOI:10.1016/j.matchemphys.2012.01.105
Basalt fiber (BF) reinforced poly(butylene succinate) (PBS) composites have been fabricated with different fiber contents by a injection molding method and their tensile, flexural and impact properties, as well as thermal stability have been investigated. The tensile and flexural properties of the PBS matrix resin are improved markedly by increasing the fiber contents in the composites. The values are relatively higher than the natural fiber/PP systems reported earlier by other research groups. The heat deflection temperature (HDT) and Vicat softening temperature (VST) of the composites are significantly higher than those of the neat PBS resin. Scanning electron microscopy (SEM) conducted on the fracture surfaces of the composites reveals superior interfacial linkage between the basalt fibers and PBS matrix. The results suggest that the BF/PBS composites may be a potential candidate of PP or PP composites to manufacturing some daily commodities to solve the “white pollution” in environmental management.Highlights► Novel basalt fiber-reinforced biodegradable poly(butylene succinate) composites have been successfully fabricated with various fiber loadings. ► The tensile and flexural properties of the PBS matrix resin are improved significantly by increasing the fiber loading in the composites. ► The impact strength of the BF/PBS composite decreases with the addition fibers primarily and increases with increasing fiber loading due to energy dissipation when the fibers are pulled out. ► Heat deflection temperature tests clearly show that the HDT of the basalt fiber reinforced PBS composites is significantly higher than the HDT of the PBS resin.
Co-reporter:Jiwu Shang, Yihe Zhang, Li Yu, Bo Shen, Fengzhu Lv, Paul K. Chu
Materials Chemistry and Physics 2012 Volume 134(2–3) pp:867-874
Publication Date(Web):15 June 2012
DOI:10.1016/j.matchemphys.2012.03.082
The morphology and microsctructure of layered graphene nanosheets/polyvinylidene fluoride (GNS/PVDF) nanocomposites fabricated by a facile and effective process are investigated. The graphene nanosheets were well dispersed and highly oriented in the matrix due to the unique preparation process. The morphology and microstructure were investigated. The results showed that the nanocomposites exhibited a much lower percolation threshold (1.29 vol%) than materials filled with carbon nanotubes. More importantly, a high dielectric constant of 63 (100 Hz) was obtained when the concentration of graphene was 1.27 vol% and it was 9 times higher than that of pure PVDF. The dielectric performance of the nanocomposites can be attributed to the homogeneous dispersion of GNS, well-aligned GNS, and resulting microcapacitor structure. An orientation mechanism for the well-aligned microstructure is proposed.Highlights► High-oriented graphene/polyvinylidene fluoride nanocomposites were fabricated. ► Enhanced dielectric properties were investigated. ► We proposed an orientation mechanism for the formation of the oriented nanocomposite.
Co-reporter:Zhichao Zhen, Yihe Zhang, Junhui Ji, Yuxia Yin, Wangshu Tong, Paul K. Chu
Materials Letters 2012 Volume 89() pp:19-21
Publication Date(Web):15 December 2012
DOI:10.1016/j.matlet.2012.08.010
Certain materials can adsorb microbes but quickly become saturated, after which no further microbial adsorption can occur. Moreover, these adsorbed microbes will reproduce at a high rate and return to the environment. The application of adsorption and antibacterial materials represents a new development in air quality improvement. In this study, composite materials, which were prepared by adding an antibacterial material to an adsorbing material, performed the functions of both types of materials. The device based on the composite materials actively adsorbed and killed airborne microbes. This material will be helpful in the sterilization and improvement of the environment.Highlights► Red mud can actively adsorb airborne microbes but cannot kill them. ► We constructed a porous material device based on red mud and an antibacterial material. ► The device can adsorb and kill microbes, thereby effectively reducing the quantity of airborne microbes.
Co-reporter:Li Yu, Yihe Zhang, Wangshu Tong, Jiwu Shang, Fengzhu Lv, Paul K. Chu, Wenmin Guo
Composites Part A: Applied Science and Manufacturing 2012 Volume 43(Issue 11) pp:2039-2045
Publication Date(Web):November 2012
DOI:10.1016/j.compositesa.2012.06.001
Hierarchical composites of polyaniline fibers on the surface of exfoliated graphite were synthesized by chemical oxidation method. The conductivity of polyaniline fibers was controlled by doping and dedoping procedures. The morphology, structure and chemical character of doped and dedoped hierarchical composites were systemically investigated by SEM, TEM, XRD, FT-IR, XPS and conductivity measurement. After dedoping procedure, polyaniline/exfoliated graphite composites were used to improve dielectric property of the electroactive polymer poly(vinylidene fluoride). The dielectric constant and loss tangent of composites were 17 and 0.06 (103 Hz) when the polyaniline/exfoliated graphite loading was 3 wt%. Of great interest was that the dielectric loss tangent of composites showed inherent low loss of poly(vinylidene fluoride) because insulating polyaniline fibers on the surface of exfoliated graphite effectively prevented direct contact of exfoliated graphite flakes in poly(vinylidene fluoride) matrix.
Co-reporter:Xuesong Li, Jiecheng Cui, Weixia Zhang, Jing Huang, Weina Li, Changxu Lin, Yin Jiang, Yihe Zhang and Guangtao Li
Journal of Materials Chemistry A 2011 vol. 21(Issue 44) pp:17953-17959
Publication Date(Web):12 Oct 2011
DOI:10.1039/C1JM11708D
In this work, a cinnamate derivative has been synthesized and infiltrated into a silica colloidal crystal template together with methyl methacrylate and ethylene glycol dimethylacrylate to construct cinnamate-based inverse-opal films. The resulting cinnamate-based photonic films can undergo reversible [2 + 2] photo-cycloaddition under ultraviolet light with different wavelengths (365 nm for cyclization and 254 nm for cleavage). Interestingly, we found that the photo-induced states of these photonic films possess more remarkable temporal and thermal stability than the reported ones based on azobenzene and spirobenzopyran derivatives. The magnitude of the shift of the Bragg diffraction peaks is also tunable, depending on the ratio of methyl methacrylate and ethylene glycol dimethylacrylate. These cinnamate-based photonic films have the potential to serve as binary systems for optical data storage, and the data stored on photonic films can be read out by detecting the reversible alternative Bragg diffraction wavelengths.
Co-reporter:Qingwei Zhu, Yihe Zhang, Jiajun Wang, Fengshan Zhou, Paul K. Chu
Solid State Sciences 2011 Volume 13(Issue 2) pp:438-443
Publication Date(Web):February 2011
DOI:10.1016/j.solidstatesciences.2010.12.008
Hollow and porous nickel microspheres with potential applications as catalysts, magnetic materials, and adsorbing materials were synthesized by self-assembly in an aqueous medium in which hydrazine hydrate acted as the reducing agent. The crystal structure, phase, particle size and magnetic performance of the hollow nickel microspheres were characterized and the effects of the template, pH value, temperature, and reaction time were evaluated. Uniform hollow nickel spheres with porous structures could be obtained at 75 °C and pH of 9–10 with a heating time of 30 min. The average diameter of the spheres was 1.4 μm and mean thickness of the sphere wall was 120 nm. Polyvinyl pyrrolidone (PK40) played an important role in the formation of the spherical template which controlled the formation of hollow spheres. Magnetic measurements indicated that the hollow nickel spheres are soft-magnetic materials with much lower coercivity and much higher saturation magnetization compared to the nickel crystals with irregular shapes.
Materials Chemistry and Physics 2011 Volume 129(1–2) pp:77-82
Publication Date(Web):15 September 2011
DOI:10.1016/j.matchemphys.2011.03.057
Hollow SiO2 nanospheres with diameter ranging from 50 to 70 nm were obtained by the template method. The core–shell structured hollow nano-SiO2@poly(methyl acrylate) nanoparticles and nano-SiO2@poly(methyl acrylate) nanoparticles/poly(methyl acrylate) composites were prepared by seed emulsion polymerization. The results indicated that the SiO2 nanoparticles showed good dispersion stability, and their compatibility with the polymer matrix was improved noticeably. The mechanical property, dynamic mechanical property and rigidity of the latex films were greatly improved when the content of silica in the composites was small. Moreover, it was found that the damping capacity could only be improved when hollow SiO2 was covalently bonded to poly(methyl acrylate) matrix.Highlights► Core-shell hollow silica/PMA composites were synthesized by grafting method. ► The hollow structure and linking style in the system was studied systematically. ► The damping capacity was improved by introduction of covalently bonded hollow SiO2.
The transparent colloidal solutions of monodisperse CeO2-based quantum dots (QDs) were prepared by heating a triethylene glycol (TEG) solution of Ce(NO3)3⋅6 H2O (and Fe(NO3)3⋅9 H2O) at 180 °C. The CeO2-based QDs were characterized by X-ray powder diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), UV/vis absorption spectra and Brunauer–Emmett–Teller (BET) surface area. CeO2-based QDs with uniform particle size below 5 nm exhibit narrow size distribution, quantum effect, good re-dispersion ability and high surface area. For the formation of these QDs, a polyol-hydrolysis mechanism is proposed. CeO2 QDs are applied in fuel borne catalysts (FBCs) for diesel soot combustion, which exhibit excellent activity at a rather low temperature, owing to the homogeneous and large number of contact points between the catalyst and the soot. The doping with Fe can further improve the selectivity to CO2.
Co-reporter:Huang Taizhong, Wu Zhu, Han Jitian, Sun Guoxin, Yu Jiemei, Cao Xianqi, Xu Naixin, Zhang Yihe
International Journal of Hydrogen Energy 2010 Volume 35(Issue 16) pp:8592-8596
Publication Date(Web):August 2010
DOI:10.1016/j.ijhydene.2010.05.009
In this paper, the structure, hydrogen storage performance, electrochemical discharge and cyclic characteristics of La0.7Mg0.3Ni3.2Co0.35−XCuX alloys were investigated using X-ray diffraction (XRD), pressure composition isotherm (PCT) and electrochemical tests. XRD tests showed that all of the alloys were composed of La2Ni7 and LaNi phases. The ratio of LaNi phase in these alloys increased with increasing substitution of Cu for Co. PCT tests showed that increasing substitution of Cu for Co resulted in the decrease of hydrogen storage capacity and the increase of plateau pressure. Electrochemical discharge tests showed that the discharge capacity increased first and then decreased with increasing substitution of Cu for Co.
Composites Science and Technology 2008 Volume 68(Issue 14) pp:2917-2921
Publication Date(Web):November 2008
DOI:10.1016/j.compscitech.2007.10.007
It was shown that chitosan and hydroxy-aluminum pillared montmorillonites were excellent materials for the removal of dyes and metal ions from effluent of dying and finishing. Chitosan, a natural biopolymeric cation, is also a promising candidate to modify montmorillonite as absorbent. Chitosan/hydroxy-aluminum pillared montmorillonite nanocomposites are expected to play a multiplex role in wastewater treatment. In this study, the nanocomposite was synthesized by incorporating hydroxy-aluminum pillared montmorillonite into chitosan solution prepared by dissolving the chitosan into diluted acetic acid. The ratio of chitosan to the cationic exchange capacity of the montmorillonite was about 1:1, 2:1, 3:1, 4:1 and 6:1, respectively. The nanocomposites were characterized by XRD (X-ray diffraction), SEM (scanning electron microscopy) and FT-IR (Fourier transform infrared spectroscopy). The experimental results indicated that the presence of hydroxy-aluminum cation was in favor of the chitosan intercalation and the interlayers of montmorillonites was intercalated with the bilayers of chitosan sheets. The nanocomposites can be used in absorption of organic and metal ions from dying and finishing effluent.
Co-reporter:Yao Wang, Hongwei Huang, Chaoming Quan, Na Tian, Yihe Zhang
Journal of Crystal Growth (1 January 2016) Volume 433() pp:1-6
Publication Date(Web):1 January 2016
DOI:10.1016/j.jcrysgro.2015.09.031
•Tb3+/Eu3+ co-doped BiPO4 nanoparticles have been obtained by a hydrothermal route.•Tunable PL emission from green to red is realized in Tb3+/Eu3+–BiPO4 phosphor.•A warmwhite color is obtained in the codoped sample by tuning the Tb3+/Eu3+ ratio.•Doped BiPO4 exhibit highly enhanced photocatalytic activity for RhB degradation.We demonstrated for first time the tunable photoluminescence (PL) properties and photocatalytic activity of the Tb3+ and Eu3+ co-doped BiPO4 assemblies. They are fabricated via a facile hydrothermal approach. Through co-doping of Eu3+ and Tb3+ ions and changing the doping ratio, the emission color of the co-doped BiPO4 phosphors can be tuned precisely from green to yellow and red. Meanwhile, a very efficient energy transfer from Tb3+ to Eu3+ can be observed. Fascinatingly, a warmwhite color has been realized in the co-doped sample by tuning the ratio of Tb3+/Eu3+ to a certain value as displayed in the CIE chromaticity diagram. The doped BiPO4 samples also exhibit significantly enhanced photocatalytic activity compared to the pristine BiPO4 pertaining to Rhodamine (RhB) degradation under UV light. This enhancement should be attributed to the trapping electron effect induced by ion doping that endows BiPO4 with high separation of photoinduced electron–hole pairs, thereby greatly promoting the photocatalytic reactivity. It was corroborated by the electrochemical impedance spectra (EIS). Moreover, the crystal structure, microstructure and optical properties of as-prepared samples were investigated in details.
Co-reporter:Xuesong Li, Jiecheng Cui, Weixia Zhang, Jing Huang, Weina Li, Changxu Lin, Yin Jiang, Yihe Zhang and Guangtao Li
Journal of Materials Chemistry A 2011 - vol. 21(Issue 44) pp:NaN17959-17959
Publication Date(Web):2011/10/12
DOI:10.1039/C1JM11708D
In this work, a cinnamate derivative has been synthesized and infiltrated into a silica colloidal crystal template together with methyl methacrylate and ethylene glycol dimethylacrylate to construct cinnamate-based inverse-opal films. The resulting cinnamate-based photonic films can undergo reversible [2 + 2] photo-cycloaddition under ultraviolet light with different wavelengths (365 nm for cyclization and 254 nm for cleavage). Interestingly, we found that the photo-induced states of these photonic films possess more remarkable temporal and thermal stability than the reported ones based on azobenzene and spirobenzopyran derivatives. The magnitude of the shift of the Bragg diffraction peaks is also tunable, depending on the ratio of methyl methacrylate and ethylene glycol dimethylacrylate. These cinnamate-based photonic films have the potential to serve as binary systems for optical data storage, and the data stored on photonic films can be read out by detecting the reversible alternative Bragg diffraction wavelengths.
Journal of Materials Chemistry A 2014 - vol. 2(Issue 40) pp:NaN8506-8506
Publication Date(Web):2014/08/01
DOI:10.1039/C4TC01097C
Recyclable, fast and visible-light responsive polymer-dispersed liquid crystal (PDLC)/graphene oxide (GO) nanocomposite films were successfully fabricated by a combination of solution casting and mechanical stretching. In the PDLC/GO nanocomposite films, one low-molecular-weight nematic LC (5CB) formed a separated phase and GO-dispersed polyvinyl alcohol (PVA) was used as the film matrix. Upon irradiation with visible light, PDLC/GO nanocomposite films showed photomechanical response, bending toward the light source along the stretching direction. Here, GO functioned as the light absorbent and nanoscale heat source to thermally induce a phase transition with 5CB from homogeneous alignment to an isotropic phase. Thus, volume contraction occurred on the surface area of the nanocomposite films due to the photothermal effect of GO, whereas little change took place in the opposite area, resulting in the visible light-induced photomechanical response in a bimetal-like mode. These PDLC/GO nanocomposite films can be potentially applied in soft actuators and micro-optomechanical systems with visible light as the energy source.
Here, we report a facile method to fabricate NiCo2O4 nanoneedles on mesocarbon microbeads (MCMB) and form a unique urchin-like core–shell structure. In this composite, the MCMB not only provided high conductivity to benefit effective electron transfer, but also offered abundant adsorption points to load the NiCo2O4 nanoneedles. The aggregation of the NiCo2O4 nanoneedles was therefore alleviated and each NiCo2O4 grain was unfolded to gain easy access to the electrolyte for efficient ion transfer. When the NiCo2O4@MCMB composite was evaluated as an electrode material for supercapacitors, a synergistic effect was exerted with high specific capacitance (458 F g−1 at 1 A g−1) and large reversibility (116% capacitance retention after 3000 cycles), both of which were of great advantage over individual MCMB and NiCo2O4 nanoneedles. The NiCo2O4@MCMB was also used to construct a symmetric supercapacitor, which showed enlarged voltage profiles and could light the LED device for a few minutes, further confirming its excellent electrochemical performance.
Co-reporter:Deyang Zhang, Yihe Zhang, Xiaowei Li, Yongsong Luo, Hongwei Huang, Jiaping wang and Paul K. Chu
Journal of Materials Chemistry A 2016 - vol. 4(Issue 2) pp:NaN577-577
Publication Date(Web):2015/11/25
DOI:10.1039/C5TA07105D
Ternary spinel metal oxide ZnCo2O4 with Co2+ at the tetrahedral sites (8a) in the spinel Co3O4 replaced by Zn2+ is promising in energy storage and an economical way to fabricate low-toxicity nanostructured ZnCo2O4 is described. Theoretical calculation confirms the rationality of the experimental scheme and elucidates the underlying reason for the increased band gap. The high electrochemical activity and excellent stability of the ZnCo2O4 NFs//ZnCo2O4 NW symmetrical device suggest large potential for energy storage applications. The fabricated device boasts a capacity of 220.6 F g−1 at a current density of 2 A g−1 and long-term cycling stability with 67.5% of the capacitance retained after 8000 cycles. The maximum energy density of 60.04 W h kg−1 at a power density of 1.4 kW kg−1 and a power density of 7 kW kg−1 at an energy density of 23.72 W h kg−1 are achieved at an operating voltage of 1.4 V. This combined experimental and theoretical study provides insights into the design and controllable preparation of nanomaterials for energy storage applications.
Different samples of gadolinium (Gd)-doped Bi2WO6 were obtained by hydrothermal means, and their photocatalytic activities for degradation of rhodamine B (RhB) under visible-light irradiation were researched. The successful incorporation of Gd3+ ions into Bi2WO6 was detected by XRD and XPS, and the prepared samples have also been characteriazed by SEM, TEM, HRTEM, DRS, and PL. The results suggested that Gd doping has great influences on the visible-light photocatalytic activity as well as the microstructure. Appropriate doping content greatly improve photocatalytic activity due to the electron shallow-trapping mechanism for the efficient separation of electron and hole pairs, and the 1% Gd–Bi2WO6 sample with flower-like structure exhibited the highest photocatalytic activity. It has already been confirmed by photocurrent generation and electrochemical impedance spectra. The present research provides a simple and valid method for improving the visible-light-responding photocatalytic activity and fabricating hierarchical architectures of Bi2WO6.
We disclose the fabrication of a mediator-free direct Z-scheme photocatalyst system BiVO4/g-C3N4 using a mixed-calcination method based on the more reliable interfacial interaction. The facet coupling occurred between the g-C3N4 (002) and BiVO4 (121), and it was revealed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). The crystal structure and optical properties of the as-prepared samples have also been characterized by Fourier-transform infrared (FTIR), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra (DRS) in details. The photocatalytic experiments indicated that the BiVO4/g-C3N4 composite photocatalysts display a significantly enhanced photocatalytic activity pertaining to RhB degradation and photocurrent generation (PC) compared to the pristine BiVO4 and g-C3N4. This remarkably improved photocatalytic performance should be attributed to the fabrication of a direct Z-scheme system of BiVO4/g-C3N4, which can result in a more efficient separation of photoinduced charge carriers than band–band transfer, thus endowing it with the much more powerful oxidation and reduction capability, as confirmed by the photoluminescence (PL) spectra and electrochemical impedance spectra (EIS). The Z-scheme mechanism of BiVO4/g-C3N4 heterostructure was verified by a series of combined techniques, including the active species trapping experiments, NBT transformation and terephthalic acid photoluminescence probing technique (TA-PL) over BiVO4/g-C3N4 composites and the pristine samples. The present work not only furthered the understanding of mediator-free Z-scheme photocatalysis, but also shed new light on the design of heterostructural photocatalysts with high-performance.
Co-reporter:Jiwu Shang, Yihe Zhang, Li Yu, Xinglong Luan, Bo Shen, Zhilei Zhang, Fengzhu Lv and Paul K. Chu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 3) pp:NaN890-890
Publication Date(Web):2012/10/26
DOI:10.1039/C2TA00602B
Graphene–polyvinylidene fluoride hybrid films (GPNs–PVDF) with a polyaniline (PANI) interlayer are fabricated by a facile and effective process. The morphology of the graphene–polyaniline nanoflakes (GPNs) is examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and the interaction between graphene and PANI is investigated by Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The GPNs have a layered structure resembling a cake with the graphene sheets sandwiched between the PANI layers. The GPNs have a uniform morphology which can be controlled by adjusting the ratio of PANI to graphene. The PANI inter-layer plays an active role in the dielectric properties of the GPNs–PVDF composites which have low dielectric loss, high breakdown field, and large energy density. The enhanced dielectric performance originates from the insulating PANI layer which not only ensures good dispersion of graphene sheets in the PVDF but also acts as an inter-particle barrier to prevent direct contact with the graphene sheets.
Co-reporter:Hongwei Huang, Ke Xiao, Shixin Yu, Fan Dong, Tierui Zhang and Yihe Zhang
Chemical Communications 2016 - vol. 52(Issue 2) pp:NaN357-357
Publication Date(Web):2015/10/22
DOI:10.1039/C5CC08239K
We herein report a facile and general approach to modulating the band energy level of semiconductors for visible-light photocatalysis via iodide surface decoration. This strategy enables the wide-band-gap Bi2O2CO3 to possess a continuously tunable band gap and profoundly boosted visible-light photocatalytic performance for dye degradation and NO removal.
Co-reporter:Na Tian, Hongwei Huang, Chengyin Liu, Fan Dong, Tierui Zhang, Xin Du, Shixin Yu and Yihe Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 33) pp:NaN17129-17129
Publication Date(Web):2015/07/14
DOI:10.1039/C5TA03669K
Development of efficient photocatalysts with both photoinduced oxidation and reduction properties is of great importance for environmental and energy applications. Herein, we report the fabrication of CeO2/g-C3N4 hybrid materials by a simple in situ co-pyrolysis method using Ce(IO3)3 and melamine as precursors. The CeO2/g-C3N4 composite catalysts possess outstanding photocatalytic activity for phenol degradation and NO removal under visible light irradiation. The degradation efficiency reaches up to 68.5 and 17.3 times higher than that of pure CeO2 and g-C3N4, respectively. Significantly, it simultaneously exhibits an enhanced hydrogen production rate, which is 1.5 times that of the pure g-C3N4. The highly enhanced photo-induced oxidation and reduction activity could be attributed to the construction of a CeO2/g-C3N4 n–n type heterojunction established by our in situ co-pyrolysis route, which enables intimate interaction across the phase interfaces; this facilitates separation and transfer of photoexcited charge carriers. This study could not only provide a facile and general approach to the fabrication of high-performance carbon-nitride-based photocatalytic materials, but also increase our understanding further on designing new hybrid composite photocatalysts for multi-functional applications.
Co-reporter:Hongwei Huang, Ying He, Xiaowei Li, Min Li, Chao Zeng, Fan Dong, Xin Du, Tierui Zhang and Yihe Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 48) pp:NaN24556-24556
Publication Date(Web):2015/11/12
DOI:10.1039/C5TA07655B
Developing high-performance photocatalytic materials is of huge significance and highly desirable for fulfilling the pressing need in environmental remediation. In this work, we demonstrate the use of bismuth nitrate Bi2O2(OH)(NO3) as an absorbing photocatalyst, which integrates multiple superiorities, like a [Bi2O2]2+ layered configuration, a non-centrosymmetric (NCS) polar structure and highly reactive {001} facets. Bi2O2(OH)(NO3) nanosheets are obtained by a facile one-pot hydrothermal route using Bi(NO3)3·5H2O as the sole raw material. Photocatalysis assessment revealed that Bi2O2(OH)(NO3) holds an unprecedented photooxidation ability in contaminant decomposition, far out-performing the well-known photocatalysts BiPO4, Bi2O2CO3, BiOCl and P25 (commercial TiO2). Particularly, it displays a universally powerful catalytic activity against various stubborn industrial contaminants and pharmaceuticals, including phenol, bisphenol A, 2,4-dichlorophenol and tetracycline hydrochloride. In-depth experimental and density functional theory (DFT) investigations co-uncovered that the manifold advantages, such as large polarizability and rational band structure, as well as exposed {001} active facets, induced robust generation of strong oxidating superoxide radicals (˙O2−) in the conduction band and hydroxyl radicals (˙OH) in the valence band, thus enabling Bi2O2(OH)(NO3) to have a powerful and durable photooxidation capability. Bi2O2(OH)(NO3) also presents high photochemical stability. This work not only rendered a highly active and stable photocatalyst for practical applications, but also laid a solid foundation for future initiatives aimed at designing new photoelectronic materials by manipulating multiple advantageous factors.
Co-reporter:Hongwei Huang, Xiaowei Li, Xu Han, Na Tian, Yihe Zhang and Tierui Zhang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 5) pp:NaN3679-3679
Publication Date(Web):2014/12/15
DOI:10.1039/C4CP04842C
We, for the first time, demonstrate band-gap-broadening as a new approach to remarkably enhance the photocatalytic activity of Br− substituted BiOI photocatalysts, which were fabricated via a facile chemical precipitation route. The successful incorporation of Br− ions into the crystal lattice of BiOI was confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). The photocatalytic experiments demonstrated that all of the Br–BiOI samples exhibited highly improved photocatalytic performances pertaining to rhodamine B (RhB) and phenol degradation under visible light (λ > 420 nm). The active species trapping and electron spin resonance (ESR) experiments also suggested that more superoxide radicals (˙O2−), serving as the main active species, were generated over Br–BiOI than pristine BiOI in the photooxidation process. Based on the results from experiments and theoretical calculations, the enhancement of photocatalytic activity should be attributed to the lowered valence band (VB) potential and enlarged band gap induced by the Br− replacement, which greatly facilitated the high separation of photoinduced electron–hole pairs, as verified by the photoluminescence (PL) experiments, electrochemical impedance spectra (EIS) and Bode-phase spectra. This work sheds light on a new method to improve the photocatalytic performance of photocatalysts.
Co-reporter:Jingwen Feng, Hongwei Huang, Shixin Yu, Fan Dong and Yihe Zhang
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 11) pp:NaN7859-7859
Publication Date(Web):2016/02/15
DOI:10.1039/C5CP06685A
The development of high-performance visible-light photocatalysts with a tunable band gap has great significance for enabling wide-band-gap (WBG) semiconductors visible-light sensitive activity and precisely tailoring their optical properties and photocatalytic performance. In this work we demonstrate the continuously adjustable band gap and visible-light photocatalysis activation of WBG BiOIO3via iodine surface modification. The iodine modified BiOIO3 was developed through a facile in situ reduction route by applying BiOIO3 as the self-sacrifice template and glucose as the reducing agent. By manipulating the glucose concentration, the band gap of the as-prepared modified BiOIO3 could be orderly narrowed by generation of the impurity or defect energy level close to the conduction band, thus endowing it with a visible light activity. The photocatalytic assessments uncovered that, in contrast to pristine BiOIO3, the modified BiOIO3 presents significantly boosted photocatalytic properties for the degradation of both liquid and gaseous contaminants, including Rhodamine B (RhB), methyl orange (MO), and ppb-level NO under visible light. Additionally, the band structure evolution as well as photocatalysis mechanism triggered by the iodine surface modification is investigated in detail. This study not only provides a novel iodine surface-modified BiOIO3 for environmental application, but also provides a facile and general way to develop highly efficient visible-light photocatalysts.
![7-Oxabicyclo[4.1.0]heptane, 1,5-dimethyl-](http://img.cochemist.com/ccimg/162300/162239-52-3.png)
![7-Oxabicyclo[4.1.0]heptane, 1,5-dimethyl-](http://img.cochemist.com/ccimg/162300/162239-52-3_b.png)
![Poly[(octahydro-1,3,5,7-tetraoxobenzo[1,2-c:4,5-c']dipyrrole-2,6(1H,3H
)-diyl)-1,4-phenyleneoxy-1,4-phenylene]](http://img.cochemist.com/ccimg/81200/81139-32-4.png)
![Poly[(octahydro-1,3,5,7-tetraoxobenzo[1,2-c:4,5-c']dipyrrole-2,6(1H,3H
)-diyl)-1,4-phenyleneoxy-1,4-phenylene]](http://img.cochemist.com/ccimg/81200/81139-32-4_b.png)
![Benzonitrile, 4-[2-[4-(pentyloxy)phenyl]diazenyl]-](/data/chemimg/81700/53510-45-5.png)
![Benzonitrile, 4-[2-[4-(pentyloxy)phenyl]diazenyl]-](/data/chemimg/81700/53510-45-5_b.png)
-1,4-PHENYLENEOXY-1,4-PHENYLENE]](http://img.cochemist.com/ccimg/40000/39940-16-4.png)
-1,4-PHENYLENEOXY-1,4-PHENYLENE]](http://img.cochemist.com/ccimg/40000/39940-16-4_b.png)
](http://img.cochemist.com/ccimg/27000/26913-06-4.png)
](http://img.cochemist.com/ccimg/27000/26913-06-4_b.png)
![Benzonitrile, 4-[2-(4-hydroxyphenyl)diazenyl]-](/data/chemimg/485700/26029-68-5.png)
![Benzonitrile, 4-[2-(4-hydroxyphenyl)diazenyl]-](/data/chemimg/485700/26029-68-5_b.png)
![POLY[OXY-1,4-PHENYLENEIMINOCARBONYL(DICARBOXYPHENYLENE)CARBONYLIMINO-1,4-PHENYLENE]](http://img.cochemist.com/ccimg/9100/9043-05-4.png)
![POLY[OXY-1,4-PHENYLENEIMINOCARBONYL(DICARBOXYPHENYLENE)CARBONYLIMINO-1,4-PHENYLENE]](http://img.cochemist.com/ccimg/9100/9043-05-4_b.png)
![Poly[oxy(1,4-dioxo-1,4-butanediyl)oxy-1,4-butanediyl]](http://img.cochemist.com/ccimg/26300/26247-20-1.png)
![Poly[oxy(1,4-dioxo-1,4-butanediyl)oxy-1,4-butanediyl]](http://img.cochemist.com/ccimg/26300/26247-20-1_b.png)
![Poly[(5,7-dihydro-1,3,5,7-tetraoxobenzo[1,2-c:4,5-c']dipyrrole-2,6(1H,3H)-diyl)-1,4-phenyleneoxy-1,4-phenylene]](http://img.cochemist.com/ccimg/25100/25036-53-7.png)
![Poly[(5,7-dihydro-1,3,5,7-tetraoxobenzo[1,2-c:4,5-c']dipyrrole-2,6(1H,3H)-diyl)-1,4-phenyleneoxy-1,4-phenylene]](http://img.cochemist.com/ccimg/25100/25036-53-7_b.png)
