Co-reporter:Huajie Huang, Gonglan Ye, Shubin Yang, Huilong Fei, Chandra Sekhar Tiwary, Yongji Gong, Robert Vajtai, James M. Tour, Xin Wang and Pulickel M. Ajayan
Journal of Materials Chemistry A 2015 vol. 3(Issue 39) pp:19696-19701
Publication Date(Web):08 Sep 2015
DOI:10.1039/C5TA05372B
The design and construction of nanostructured electrode catalysts with high activity at low cost are crucial elements in fuel cell technologies. Here, we demonstrate a combined hydrothermal self-assembly, freeze-drying, and thermal annealing approach for the fabrication of a hybrid catalyst made from nanosized Pt particles and three-dimensional (3D) nitrogen-doped graphene nanoribbons (N-GNRs). The resulting 3D architecture possesses a large surface area, interconnected porous networks, uniform nitrogen distribution, extremely small sizes of Pt NPs and good electrical conductivity, which are highly desirable for electrocatalysis of the methanol oxidation reaction. As a consequence, remarkable electrocatalytic properties including exceptional electrocatalytic activity, strong poison tolerance as well as superior long-term stability are achieved for the Pt/N-GNR architecture, all of which outperform those observed for Pt/Vulcan XC-72 (Pt/C), Pt/carbon nanotube (Pt/CNT) and Pt/undoped GNR (Pt/GNR) catalysts.
Co-reporter:Huajie Huang, Wenyao Zhang, Yongsheng Fu, Xin Wang
Electrochimica Acta 2015 Volume 152() pp:480-488
Publication Date(Web):10 January 2015
DOI:10.1016/j.electacta.2014.11.162
The rational combination of transition metal oxides and carbon materials has been regarded as an efficient way of accessing the next-generation electrode materials for electrochemical capacitors. Here we demonstrate a facile synthesis of nanostructured MnO2 supported on carbon nanotubes (CNTs) via a direct redox route. By varying the reaction time, it can be convenient to control the growth density of MnO2 as well as the structural integrity of CNTs, which endow the novel hybrids with adjustable electrochemical performance. As a consequence, the resulting MnO2-CNT electrodes exhibit a maximum specific capacitance of 247.9 F g-1, with good rate capability and extraordinary cycling life stability (92.8% retention of initial capacitance after 5000 cycles), suggesting such materials have great potential in constructing high-performance energy-storage systems.Nanostructured MnO2 with controllable densities is successfully deposited on carbon nanotubes through a facile and straightforward redox approach. The as-prepared MnO2-carbon nanotube hybrids exhibit outstanding capacitive properties including high specific capacitances, good rate capability and excellent cyclic stability.
Co-reporter:Pan Xiong, Lele Peng, Dahong Chen, Yu Zhao, Xin Wang, Guihua Yu
Nano Energy 2015 Volume 12() pp:816-823
Publication Date(Web):March 2015
DOI:10.1016/j.nanoen.2015.01.044
•An all-nanosheet-based full Li-ion battery is fabricated.•ZnMn2O4–graphene hybrid nanosheet and LiFePO4 nanosheet are employed as high-rate anode and cathode, respectively.•This all-nanosheet-based full battery shows high rate capability and mechanical flexibility.Here we report an all-nanosheet-based Li-ion full battery using ZnMn2O4–graphene hybrid nanosheet and LiFePO4 nanosheet as anode and cathode, respectively. The short Li ion diffusion length and open charge transport channel of these two-dimensional (2D) nanostructures enable rapid charge and discharge rate. The all-nanosheet-based full battery exhibits superior rate capability and cycling stability, compared to the control full battery using conventional graphite anode and commercial LiFePO4 cathode. Furthermore, flexible full batteries using these 2D nanostructured electrodes are fabricated in pouch cell form, and exhibit impressive electrochemical stability without structural failure and performance loss under various mechanical bending states.An all-nanosheet-based full battery with ZnMn2O4–graphene hybrid nanosheet anode and LiFePO4 nanosheet cathode is fabricated with high rate capability and cycling stability.
Co-reporter:Huajie Huang;Shubin Yang;Robert Vajtai;Pulickel M. Ajayan
Advanced Materials 2014 Volume 26( Issue 30) pp:5160-5165
Publication Date(Web):
DOI:10.1002/adma.201401877
Co-reporter:Huajie Huang and Xin Wang
Journal of Materials Chemistry A 2014 vol. 2(Issue 18) pp:6266-6291
Publication Date(Web):06 Jan 2014
DOI:10.1039/C3TA14754A
With the continuously increasing demand of energy along with depletion of conventional fossil fuel reserves and the rapidly escalating environmental problems, direct methanol fuel cells (DMFCs) as alternative green and sustainable power sources have aroused tremendous research interest in academic and engineering circles. In order to achieve high power density as well as low production cost of DMFCs, the well-designed and fabricated anode catalysts with controllable composition, architecture and morphology have been regarded as a key point for realizing high-performance. In this aspect, carbon materials, as building blocks, offer a great potential to play a key role in constructing advanced hybrid catalysts due to their exceptional physicochemical properties, such as high specific surface area, superior electronic conductivity, excellent stability and so on. This review summarizes the recent significant progress in the design and fabrication of novel carbon-based anode catalysts via various strategies and their applications in methanol oxidation reaction. Finally, perspectives on the challenges and research trends in this emerging area are also discussed.
Co-reporter:Pan Xiong, Borui Liu, Vincent Teran, Yu Zhao, Lele Peng, Xin Wang, and Guihua Yu
ACS Nano 2014 Volume 8(Issue 8) pp:8610
Publication Date(Web):July 29, 2014
DOI:10.1021/nn5041203
Hybrid inorganic/graphene two-dimensional (2D) nanostructures can offer vastly open large surface areas for ion transport and storage and enhanced electron transport, representing a promising material platform for next-generation energy storage. Here we report chemically integrated hybrid ZnMn2O4/graphene nanosheets synthesized via a facile two-step method for greatly enhanced lithium storage capability. The hybrid 2D nanosheets are composed of ultrafine ZnMn2O4 nanocrystals with a mean diameter of ∼4 nm attached to and well dispersed on the surface of reduced graphene oxide sheets. The hybrid nanosheets based anode offers a high capacity of ∼800 mAh g–1 at a current rate of 500 mA g–1, excellent rate capability, and long-term cyclability with reversible capacity of ∼650 mAh g–1 over 1500 cycles at a current density of 2000 mA g–1. Moreover, when tested in a temperature range of ∼0–60 °C, the designed anode can maintain high discharge capacities from 570 to 820 mAh g–1.Keywords: energy storage; graphene; Li-ion battery; mixed transitional-metal oxides; two-dimensional nanosheets; ZnMn2O4
Co-reporter:Jin Li, Xiaoheng Liu, Qiaofeng Han, Xiaxi Yao and Xin Wang
Journal of Materials Chemistry A 2013 vol. 1(Issue 4) pp:1246-1253
Publication Date(Web):08 Nov 2012
DOI:10.1039/C2TA00382A
Self-assembly can offer a very powerful tool for the design of novel materials and many different templates have been found to direct the formation of microstructures. In this article, we report a simple method for the self-assembly of three-dimensional (3D) WO3 nanotube bundles. It is demonstrated that not only can NaHSO4 act as a reactant, but also, more importantly, it played multiple key roles in the self-assembly processes, while NH4HSO4 and KHSO4 have none of these functions at all. As suggested, at first, WO3 ordered and layered structures can be generated by the hydrothermal reaction of NaHSO4 with Na2WO4 at 180 °C, and then sodium ions (Na+) inserted into the layer cause a continual curl of the WO3 outer-slice by the repel force of static electricity between Na+ ions and H+ ions on the surface of the WO3 slice. Herein, Na+ ions can dramatically promote the formation of WO3 single crystal slices, which are precursors of the self-assembly, and SO42− ions can bridge the WO3 slices as well as the nanotubes. In addition, it is found that the WO3 nanotube bundles still keep their original aggregation after template removal, and the bundle can be disassembled gradually under a long treatment time of aqueous ultrasonication. Furthermore, the application in wastewater treatment of WO3 nanotube bundles has been investigated.
Co-reporter:Huajie Huang, Qun Chen, Mingyang He, Xiaoqiang Sun, Xin Wang
Journal of Power Sources 2013 Volume 239() pp:189-195
Publication Date(Web):1 October 2013
DOI:10.1016/j.jpowsour.2013.03.133
•A ternary Pt/MnO2/graphene nanohybrid is synthesized for the first time.•Graphene can be used as both a green reductant and an ideal substrate.•Ultrafine Pt nanoparticles are highly dispersed on MnO2-modified graphene sheets.•Pt/MnO2/graphene shows an ultrahigh catalytic activity toward methanol oxidation.Ultrafine Pt nanoparticles with an average diameter of only 1.7 nm are uniformly dispersed onto MnO2-functionalized graphene sheets by a facile and cost-effective method. In such a ternary Pt/MnO2/graphene sheets (Pt/MnO2/GS) nanohybrid, each component provides unique and critical function to achieve optimized utilization of metallic platinum, allowing it to express ultrahigh electrocatalytic activity ability in methanol oxidation (the forward anodic peak current density is up to 1224 mA mg−1) in comparison with Pt/graphene sheets (Pt/GS), Pt/Vulcan XC-72 (Pt/XC-72) and Pt/MnO2/XC-72 catalysts. This work could provide new insights into the fabrication of the next generation high-performance electrocatalyst and promote their practical application in fuel-cell technologies.
Co-reporter:Huajie Huang and Xin Wang
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 25) pp:10367-10375
Publication Date(Web):22 Apr 2013
DOI:10.1039/C3CP51569A
One great challenge in the development of portable fuel cell systems is to explore novel electrocatalysts with better performance and lower costs. Here we report a facile strategy to fabricate a ternary nanocomposite based on Pd/MnO2 nanolamella–graphene sheets (Pd/MNL/GS) and demonstrate its application as a multifunctional catalyst for both the direct formic acid fuel cell (DFAFC) and direct methanol fuel cell (DMFC). The developed route rationally utilizes graphene as both a green reducing agent in the synthesis of MnO2 nanolamella and a superior supporting material for growing and supporting Pd nanoparticles (NPs). Whether for formic acid oxidation or methanol oxidation, the as-prepared Pd/MNL/GS hybrid has extremely large electrochemically active surface area (ECSA) values and exhibits significantly high forward peak current densities, both of which are nearly 3 times greater than those of the Pd/GS catalyst and 6 times the Pd/Vulcan XC-72 catalyst, revealing that metal Pd can be effectively utilized in the presence of promoter components (MNL and GS). Therefore, such a ternary composite with a sophisticated 2D configuration may bring new design opportunities of high-performance energy conversion devices in the future.
Co-reporter:Pan Xiong, Junwu Zhu, and Xin Wang
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 48) pp:17126
Publication Date(Web):November 13, 2013
DOI:10.1021/ie402437k
We report a facile strategy to fabricate a cadmium sulfide–ferrite (CdS–MFe2O4, M = Zn, Co) nanocomposite with differing ferrite content via a two-step hydrothermal method and demonstrate its application as a magnetically recyclable photocatalyst with enhanced visible-light-driven photocatalytic activity and photostability. The photocatalytic activities of as-prepared photocatalysts are evaluated by the degradation of rhodamine B (RhB) and 4-chlorophenol (4-CP) in aqueous solution under visible-light irradiation. Compared with pure CdS, both CdS–ZnFe2O4 and CdS–CoFe2O4 show more broad absorption in the visible-light region, which favors the visible-light utilization for better photocatalytic performance. Moreover, the surface area of cadmium sulfide–ferrite is much higher than that of pure CdS, also resulting in enhanced photocatalytic activity. Furthermore, the synergic effects of CdS and ferrites can reduce the recombination probability of photogenerated electron–hole pairs and enhance the charge separation efficiency, leading to high photocatalytic performance and remarkable inhibited photocorrosion.
Co-reporter:Pan Xiong, Lianjun Wang, Xiaoqiang Sun, Binhai, Xu, and Xin Wang
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 30) pp:10105-10113
Publication Date(Web):July 4, 2013
DOI:10.1021/ie400739e
A straightforward strategy is designed for the fabrication of magnetically recyclable ternary titania–cobalt ferrite–polyaniline (P25-CoFe2O4-PANI) photocatalysts with differing P25/CoFe2O4 ratio. The pseudo-second-order and Langmuir models are found to be most suitable for describing the adsorption of methyl orange (MO) onto the photocatalysts. The photocatalytic activity of P25-CoFe2O4-PANI is evaluated by the degradation of various dyes under visible light irradiation, and the results show that the ternary P25-CoFe2O4-PANI photocatalyst exhibits high photocatalytic activity due to the good adsorption capacity of the hybrid and the introduction of P25, which can further improve the separation of the light-induced electron–hole pairs. The degradation of anionic dyes is much more effective than that of cationic dyes due to the negatively charged groups of anionic dyes undergo electrostatic attraction with the positively charged backbone of PANI, and such an effective adsorption helps in promoting the degradation.
Co-reporter:Sheng Chen; Junwu Zhu;Ling Qiu; Dan Li; Xin Wang
Chemistry - A European Journal 2013 Volume 19( Issue 23) pp:7631-7636
Publication Date(Web):
DOI:10.1002/chem.201300262
Abstract
The development of novel nanostructured electrode materials with high performance and based on abundant elements is a key element in the societal pursuit of sustainable energy. Graphene-based structures with rich macroporosity and high conductive networks are promising components to develop novel electrode materials. Herein, we described a facile procedure to confine Ni(OH)2 particles in a graphene film, leading to a new sandwich-like hybrid structure. The hybrid film offers simultaneously ordered ion diffusion channels and high electrical conductivity, which facilitate the improvement of both electrode kinetics and electrochemical stability, thus leading to high capacitance, fast rate capability, and stable cycle life as supercapacitor materials. This work provides a facile pathway for optimized structures for electrode materials, and represents a benefit for the global issues of energy shortage and environmental pollution.
Co-reporter:Xifeng Xia, Qingli Hao, Wu Lei, Wenjuan Wang, Dongping Sun and Xin Wang
Journal of Materials Chemistry A 2012 vol. 22(Issue 33) pp:16844-16850
Publication Date(Web):03 Jul 2012
DOI:10.1039/C2JM33064D
Well-designed nanostructures of a ternary nanocomposite, graphene/Fe2O3/polyaniline, are fabricated via a two-step approach. Graphene oxide is reduced by Fe2+ and well-dispersed by loading α-Fe2O3 nanoparticles (20–70 nm in size). A thin film of polyaniline is in situ polymerized on the graphene/Fe2O3 surfaces for the fabrication of its ternary composite. Among the composites obtained at different ratios of graphene/Fe2O3 to polyaniline, the ternary graphene/Fe2O3/polyaniline with a ratio of 2:1 exhibits a high specific capacitance of 638 F g−1 in 1 M KOH at a scan rate of 1 mV s−1 and experiences only a negligible decay of 8% after 5000 cycles. It also shows a higher energy density at high power density than other ternary or binary composites of the three components, respectively. The extraordinary electrochemical performance of the composite arises from the well-designed structural advantages of the ternary nanocomposite, and the good combination and synergistic effects among the three components. Graphene sheets, as the conducting frameworks for sustaining polyaniline and Fe2O3, can separate and disperse well in the composite due to the existence of Fe2O3. On the other hand, the thin film of polyaniline on the surface of graphene/Fe2O3 not only enhances the surface area, but also restricts the dissolution, aggregation and volume changes of Fe2O3 during charge–discharge cycling. Additionally, the existence of Fe2O3 is helpful to increase the rate stability of the ternary composite. The ternary composites with synergistic effects can take advantage of both Faradaic and non-Faradaic processes for capacity-charge storage with excellent electrochemical properties.
Co-reporter:Xifeng Xia, Qingli Hao, Wu Lei, Wenjuan Wang, Hualan Wang and Xin Wang
Journal of Materials Chemistry A 2012 vol. 22(Issue 17) pp:8314-8320
Publication Date(Web):16 Mar 2012
DOI:10.1039/C2JM16216D
Reduced-graphene oxide/molybdenum oxide/polyaniline ternary composites, RGO(MP), for use as electrode materials for high energy density supercapacitors, were firstly synthesized using a one-step method with Mo3O10(C6H8N)2·2H2O and graphene oxide (GO) as precursors. When the mass ratio of Mo3O10(C6H8N)2·2H2O to GO is 8:1, the resulting composite RGO(MP)8 shows excellent electrochemical performance with a maximum specific capacitance of 553 F g−1 in 1M H2SO4 and 363 F g−1 in 1 M Na2SO4 at a scan rate of 1 mV s−1. Its energy density reaches 76.8 W h kg−1 at a power density of 276.3 W kg−1, and 28.6 W h kg−1 at a high power density of 10294.3 W kg−1 in H2SO4. While in Na2SO4, the energy density achieves 72.6 W h Kg−1 at a power density of 217.7 W kg−1 and 13.3 W h Kg−1 at power density of 3993.8 W kg−1, respectively. The composite also presents good cycling stability (86.6, 73.4% at 20 mV s−1 after 200 cycles in 1 M H2SO4 and Na2SO4, respectively).
Co-reporter:Wenjuan Wang, Qingli Hao, Wu Lei, Xifeng Xia and Xin Wang
RSC Advances 2012 vol. 2(Issue 27) pp:10268-10274
Publication Date(Web):31 Aug 2012
DOI:10.1039/C2RA21292G
A ternary electrode material, based on graphene, tin oxide (SnO2) and polypyrrole (PPy) was obtained via one–pot synthesis. The graphene/SnO2/PPy (GSP) nanocomposite is composed of a thin conducting film of PPy on the surface of graphene/SnO2 (GS). An enhanced specific capacitance (616 F g−1) of GSP was obtained at 1 mV s−1 in 1 M H2SO4 compared with GS (80.2 F g−1) and PPy (523 F g−1). The GSP electrode shows better cycle stability and no obvious decay after 1000 galvanostatic cycles at 1 A g−1. Its specific power density and energy density can reach 9973.26 W kg−1, and 19.4 W h kg−1, respectively. The excellent electrochemical performance arises from the well-designed structure advantages, the good combination of components and the synergistic effect between the three components. Well-dispersed graphene is used as a framework for sustaining the pseudocapacitive materials of SnO2 and PPy. The PPy film restricts the aggregation and volume change of SnO2 during charge–discharge cycling, and also enhances the surface area. The electrochemical results show that the ternary composite of GSP is a promising candidate electrode material for high-performance supercapacitors.
Co-reporter:Qiao-Feng Han, Fang Jin, Wen-Jun Yang, Dong-Ping Sun, Xin Wang
Materials Letters 2012 Volume 69() pp:10-12
Publication Date(Web):15 February 2012
DOI:10.1016/j.matlet.2011.10.111
Single-crystalline PbS hexagonal nanoplates and microspheres assembled by nanocubes were synthesized via two-phase methods, where CS2 acts as both sulfur source and one reaction medium, and N, N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) acts as the other medium to dissolve lead source. The products were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron energy spectra (XPS). After 4 days' reaction at room temperature, the PbS nanoplates with an edge length of approximately 400 nm and thicknesses of about 50 nm were generated in DMF solution, while the nanocube-based PbS microspheres were obtained if using DMSO as solution. The possible formation mechanism of PbS nanoplates and microspheres has been elucidated.Highlights►A metal inorganic precursor instead of organic precursor was used. ►Plate-like PbS was obtained via two-phase methods. ►PbS microspheres assembled by nanocubes were synthesized by varying the solution.
Co-reporter:Qiaofeng Han, Shanshan Sun, Dongping Sun, Junwu Zhu and Xin Wang
RSC Advances 2011 vol. 1(Issue 7) pp:1364-1369
Publication Date(Web):07 Oct 2011
DOI:10.1039/C1RA00379H
Starting from molecular precursors antimonyO-ethyldithiocarbonate (ethyl xanthate, (C2H5OCS2)3Sb), ultralong Sb2S3 nanowires with a diameter in the range of 5–10 nm were easily synthesized at room temperature by employing ethylenediamine both as solvent and a bidentate ligand. By varying crystallization duration, the shape of Sb2S3 particles evolved from belts, tubes and finally to nanowires through the well-known rolling process. This synthetic route was workable for the preparation of other chalcogenides such as ZnS and PbS particles with well-defined nanostructures. The photocatalytic experiment of the as-prepared Sb2S3 nanowires under visible light indicated that the photodegradation ratio of methyl orange in aqueous solution was up to 95% after 25 min of irradiation, which was much better than that of its bulk counterparts under the same conditions. High efficiency resulted from the broad spectrum response and high surface area nature of the as-synthesized Sb2S3 nanowires.
Co-reporter:Qingli Hao;Hualan Wang;Xujie Yang;Lude Lu
Nano Research 2011 Volume 4( Issue 4) pp:323-333
Publication Date(Web):2011 April
DOI:10.1007/s12274-010-0087-4
Co-reporter:Lu Wang;Xiaoheng Liu;Xujie Yang
Journal of Materials Science: Materials in Electronics 2011 Volume 22( Issue 6) pp:601-606
Publication Date(Web):2011 June
DOI:10.1007/s10854-010-0184-x
One-dimensional Co3O4 nanowires have been prepared by utilizing the ordered mesoporous silica material SBA-15 as template. The results of transmission electron microscope (TEM) and N2 adsorption–desorption characterizations show that the Co3O4 nanowires possess a uniform size and a large Brunauer-Emmett-Teller (BET) surface area. Its electrochemical performance was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques in various concentration of KOH solution. This nanomaterial shows a small resistance, a high specific capacitance (SC), and a strong cyclic stability. The maximal SC value of 373 F·g−1 was obtained in 6 M electrolyte under the scan speed of 3 mV·s−1 at the first CV cycle. After 500 CV cycles, the SC value is about 90% of the original value. It is considered that the short path of ion transfer given by nanomaterial brought on the great pseudo capacitance performance.
Co-reporter:Hualan Wang, Qingli Hao, Xujie Yang, Lude Lu and Xin Wang
Nanoscale 2010 vol. 2(Issue 10) pp:2164-2170
Publication Date(Web):06 Aug 2010
DOI:10.1039/C0NR00224K
A flexible graphene/polyaniline hybrid material as a supercapacitor electrode was synthesized by an in situ polymerization-reduction/dedoping-redoping process. This product was first prepared in an ethylene glycol medium, then treated with hot sodium hydroxide solution to obtain the reduced graphene oxide/polyaniline hybrid material. Sodium hydroxide also acted as a dedoping reagent for polyaniline in the composite. After redoping in an acidic solution, the thin, uniform and flexible conducting graphene/polyaniline product was obtained with unchanged morphology. The chemical structure of the materials was characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. The composite material showed better electrochemical performances than the pure individual components. A high specific capacitance of 1126 F g−1 was obtained with a retention life of 84% after 1000 cycles for supercapacitors. The energy density and power density were also better than those of pure component materials.
Co-reporter:Hualan Wang, Qingli Hao, Xujie Yang, Lude Lu and Xin Wang
ACS Applied Materials & Interfaces 2010 Volume 2(Issue 3) pp:821
Publication Date(Web):March 4, 2010
DOI:10.1021/am900815k
Graphene oxide, a single layer of graphite oxide (GO), has been used to prepare graphene oxide/polyaniline (PANI) composite with improved electrochemical performance as supercapacitor electrode by in situ polymerization using a mild oxidant. The composites are synthesized under different mass ratios, using graphite as start material with two sizes: 12 500 and 500 mesh. The result shows that the morphology of the prepared composites is influenced dramatically by the different mass ratios. The composites are proposed to be combined through electrostatic interaction (doping process), hydrogen bonding, and π−π stacking interaction. The highest initial specific capacitances of 746 F g−1 (12 500 mesh) and 627 F g−1 (500 mesh) corresponding to the mass ratios 1:200 and 1:50 (graphene oxide/aniline) are obtained, compared to PANI of 216 F g−1 at 200 mA g−1 by charge−discharge analysis between 0.0 and 0.4 V. The improved capacitance retention of 73% (12 500 mesh) and 64% (500 mesh) after 500 cycles is obtained for the mass ratios 1:23 and 1:19 compared to PANI of 20%. The enhanced specific capacitance and cycling life implies a synergistic effect between two components. This study is of significance for developing new doped PANI materials for supercapacitors.Keywords: electrochemical properties; graphene; graphene oxide; polyaniline; supercapacitor
Co-reporter:Weiguang Zhang, Lili Zhang, Hui Zhong, Lude Lu, Xujie Yang, Xin Wang
Materials Characterization 2010 Volume 61(Issue 2) pp:154-158
Publication Date(Web):February 2010
DOI:10.1016/j.matchar.2009.11.005
Stearic acid method (SAM) was developed to synthesize series of pyrochlore Ln2Ti2O7 (Ln = Sm, Gd, Dy, Er) nanocrystals. The synthesis process was monitored by X-ray diffraction, Thermal–gravimetric–differential thermal analysis and Fourier Transform InfraRed methods. Comparing with traditional solid-state reaction (SSR), Ln2Ti2O7 can be synthesized at relatively low temperature (700–800 °C) with shortened reaction time (2–4 h). The average particle size of Ln2Ti2O7 was greatly reduced (ca. 40 nm) and the BET surface area was increased (ca. 12 m2/g) by using SAM. From the X-ray diffraction patterns, we found that Ln has an effect on the crystal structure of Ln2Ti2O7, every lattice peak shifted to larger angle slightly with the increasing atomic number of Ln. Also, the lattice constant of Ln2Ti2O7 was calculated by Jade.5 and found it decreased along with the decrease of ionic radius of Ln3+. The morphology of obtained Ln2Ti2O7 was determined by transmission electron microscopy technique. Results showed that the obtained Ln2Ti2O7 were all square-like and the interplanar distance of Ln2Ti2O7 (Ln = Sm, Gd, Dy, Er) according to (111) plane was 0.65, 0.64, 0.63, and 0.62 nm respectively, which was measured from High Resolution Transmission Electron Microscopy images. Possible reason for this phenomenon was presented.
Co-reporter:Hualan Wang, Qingli Hao, Xujie Yang, Lude Lu, Xin Wang
Electrochemistry Communications 2009 Volume 11(Issue 6) pp:1158-1161
Publication Date(Web):June 2009
DOI:10.1016/j.elecom.2009.03.036
A novel high-performance electrode material based on fibrillar polyaniline (PANI) doped with graphene oxide sheets was synthesized via in situ polymerization of monomer in the presence of graphene oxide, with a high conductivity of 10 S cm−1 at 22 °C for the obtained nanocomposite with a mass ratio of aniline/graphite oxide, 100:1. Its high specific capacitance of 531 F/g was obtained in the potential range from 0 to 0.45 V at 200 mA/g by charge–discharge analysis compared to 216 F/g of individual PANI. The doping and the ratio of graphene oxide have a pronounced effect on the electrochemical capacitance performance of the nanocomposites.
Co-reporter:Jun-ling Ji;Xu-Jie Yang;Lu-De Lu
Journal of Applied Polymer Science 2009 Volume 113( Issue 6) pp:3774-3781
Publication Date(Web):
DOI:10.1002/app.30215
Abstract
The volume of water consumed by human beings has increased dramatically in recent years while water supply has remained constant; both demographic growth and the expansion of industrial activity require more water consumption. The textile industry is undoubtedly one of the most pressured industries that need water intensively. Efficient use of water tends to be a crucial subject for the dyeing industry. In this study, melamine resin microcapsules containing pure disperse dyes were prepared by in situ polymerization. The microcapsules were characterized on the basis of structure, morphologies, mean particle size, and size distribution. The dyeing behaviors of microencapsulated disperse dyes (MDDs) were evaluated on polyester fabrics in the absence of auxiliaries. Its effluent can be reused several times after being simply filtered and can be used as solvent for PET fabric scouring. The treated fabrics exhibited satisfactory levelness and fastness properties. MDDs can be used in dyeing PET, without using surfactants, and the effluents can be recycled and reused. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Junwu Zhu, Huiping Bi, Yanping Wang, Xin Wang, Xujie Yang, Lude Lu
Materials Letters 2008 Volume 62(Issue 14) pp:2081-2083
Publication Date(Web):15 May 2008
DOI:10.1016/j.matlet.2007.11.020
We describe a facile route for the synthesis of Cu2O cubes using CuO as the precursor and hydrazine hydrate as the reducing agent. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations indicate that the Cu2O products are composed of cubes with an edge length of 0.7–1.2 μm. This method is surfactant-free, and well-dispersed Cu2O cubes can be obtained through this route. The presence of small amounts of ions in reaction solution has a great influence on the morphology of Cu2O products.
Co-reporter:Qiaofeng Han, Jian Chen, Juan Lu, Xujie Yang, Lude Lu, Xin Wang
Materials Letters 2008 Volume 62(Issue 14) pp:2050-2052
Publication Date(Web):15 May 2008
DOI:10.1016/j.matlet.2007.11.012
Co-reporter:Chi Zhang, Yinglin Song, Xin Wang
Coordination Chemistry Reviews 2007 Volume 251(1–2) pp:111-141
Publication Date(Web):January 2007
DOI:10.1016/j.ccr.2006.06.007
This contribution presents an overview of the structural features and third-order optical non-linearities of the principal classes of transition heterothiometallic clusters, and demonstrates how synthetic coordination chemistry can offer a very large variety of NLO performances in relation to the different applicable heavy transition metals and the cluster configurations, the molecular symmetry and structural rigidity of the cluster compounds, the size of the energy gap between HOMO and LUMO as well as the π-donating peripheral ligands. Such clusters can very well satisfy the different heavy demands of third-order NLO materials such as absorption, refraction, switch and most importantly, optical limiting, depending on the subtle interplay of structure–function relationships. Correlations between the structural characteristics and the non-linear optical functions of these heterothiometallic clusters are discussed and examined. Recent advances and perspectives of these clusters as NLO materials are also described.
Co-reporter:Chao Huang;Xu-Jie Yang;Lu-De Lu
Chinese Journal of Chemistry 2005 Volume 23(Issue 11) pp:
Publication Date(Web):30 NOV 2005
DOI:10.1002/cjoc.200591503
Multi-protection is a principle in security management, and the use of anti-explosion and fireproof agents is a crucial part of it. In this paper, the properties of nano-oxide particles in the field of anti-explosion and fireproof were analyzed. The sedimentation velocity of nanometer particles was calculated. CH4 was taken as an example, and its combustion mechanism of the initial stages was concluded. The effects of 15 oxides on molecular energies of the reaction system were calculated with program Hyperchem 6, and the possible contact manner between radicals and oxides was got. It was concluded that oxides, such as ZrO2, could combine with radicals, and thus prevent the combustion reaction. It was found that the nano-ZrO2 eruptively generated aerosol is superior to other counterparts in serving as the anti-explosion and fireproof agent, and therefore, will play an increasingly important role in the security management.
Co-reporter:Dan Li, Juan Yang, Lili Zhang, Xin Wang, Lude Lu and Xujie Yang
Journal of Materials Chemistry A 2002 vol. 12(Issue 6) pp:1796-1799
Publication Date(Web):30 Apr 2002
DOI:10.1039/B109759H
Nanoscale layered tetratitanate K2Ti4O9 powders were prepared at relatively low temperature by a stearic acid method. The structures of the titanates and the products which had undergone H+, Ag+ exchange and intercalated by propylamine and NH2(CH2)3Si(OC2H5)3
(APS) were investigated by XRD, TEM, TG and BET analysis. Compared with the larger-size products prepared by a conventional solid state reaction, the nanoscale K2Ti4O9 takes in more intercalating molecules and leads to larger interlayer distances in the intercalated products, which may facilitate the exfoliation of the layered compound.
Co-reporter:Dan Li, Donghui Wu, Xin Wang, Lude Lu, Xujie Yang
Materials Research Bulletin 2001 Volume 36(13–14) pp:2437-2442
Publication Date(Web):1 November 2001
DOI:10.1016/S0025-5408(01)00735-8
A rapid and simple method was developed to prepare porous Fe2O3/SiO2 nanocomposites by combustion of stearic acid precursors. The composites were characterized by FTIR, XRD, and BET specific area measurement. The results showed that the composites were porous, and the porous structure was dependent on the content of SiO2. The resulting composites impregnated by H2SO4 showed good catalytic activity for the esterifcation of acetic acid and butanol.
Co-reporter:Huajie Huang and Xin Wang
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 25) pp:NaN10375-10375
Publication Date(Web):2013/04/22
DOI:10.1039/C3CP51569A
One great challenge in the development of portable fuel cell systems is to explore novel electrocatalysts with better performance and lower costs. Here we report a facile strategy to fabricate a ternary nanocomposite based on Pd/MnO2 nanolamella–graphene sheets (Pd/MNL/GS) and demonstrate its application as a multifunctional catalyst for both the direct formic acid fuel cell (DFAFC) and direct methanol fuel cell (DMFC). The developed route rationally utilizes graphene as both a green reducing agent in the synthesis of MnO2 nanolamella and a superior supporting material for growing and supporting Pd nanoparticles (NPs). Whether for formic acid oxidation or methanol oxidation, the as-prepared Pd/MNL/GS hybrid has extremely large electrochemically active surface area (ECSA) values and exhibits significantly high forward peak current densities, both of which are nearly 3 times greater than those of the Pd/GS catalyst and 6 times the Pd/Vulcan XC-72 catalyst, revealing that metal Pd can be effectively utilized in the presence of promoter components (MNL and GS). Therefore, such a ternary composite with a sophisticated 2D configuration may bring new design opportunities of high-performance energy conversion devices in the future.
Co-reporter:Xifeng Xia, Qingli Hao, Wu Lei, Wenjuan Wang, Dongping Sun and Xin Wang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 33) pp:NaN16850-16850
Publication Date(Web):2012/07/03
DOI:10.1039/C2JM33064D
Well-designed nanostructures of a ternary nanocomposite, graphene/Fe2O3/polyaniline, are fabricated via a two-step approach. Graphene oxide is reduced by Fe2+ and well-dispersed by loading α-Fe2O3 nanoparticles (20–70 nm in size). A thin film of polyaniline is in situ polymerized on the graphene/Fe2O3 surfaces for the fabrication of its ternary composite. Among the composites obtained at different ratios of graphene/Fe2O3 to polyaniline, the ternary graphene/Fe2O3/polyaniline with a ratio of 2:1 exhibits a high specific capacitance of 638 F g−1 in 1 M KOH at a scan rate of 1 mV s−1 and experiences only a negligible decay of 8% after 5000 cycles. It also shows a higher energy density at high power density than other ternary or binary composites of the three components, respectively. The extraordinary electrochemical performance of the composite arises from the well-designed structural advantages of the ternary nanocomposite, and the good combination and synergistic effects among the three components. Graphene sheets, as the conducting frameworks for sustaining polyaniline and Fe2O3, can separate and disperse well in the composite due to the existence of Fe2O3. On the other hand, the thin film of polyaniline on the surface of graphene/Fe2O3 not only enhances the surface area, but also restricts the dissolution, aggregation and volume changes of Fe2O3 during charge–discharge cycling. Additionally, the existence of Fe2O3 is helpful to increase the rate stability of the ternary composite. The ternary composites with synergistic effects can take advantage of both Faradaic and non-Faradaic processes for capacity-charge storage with excellent electrochemical properties.
Co-reporter:Xifeng Xia, Qingli Hao, Wu Lei, Wenjuan Wang, Hualan Wang and Xin Wang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 17) pp:NaN8320-8320
Publication Date(Web):2012/03/16
DOI:10.1039/C2JM16216D
Reduced-graphene oxide/molybdenum oxide/polyaniline ternary composites, RGO(MP), for use as electrode materials for high energy density supercapacitors, were firstly synthesized using a one-step method with Mo3O10(C6H8N)2·2H2O and graphene oxide (GO) as precursors. When the mass ratio of Mo3O10(C6H8N)2·2H2O to GO is 8:1, the resulting composite RGO(MP)8 shows excellent electrochemical performance with a maximum specific capacitance of 553 F g−1 in 1M H2SO4 and 363 F g−1 in 1 M Na2SO4 at a scan rate of 1 mV s−1. Its energy density reaches 76.8 W h kg−1 at a power density of 276.3 W kg−1, and 28.6 W h kg−1 at a high power density of 10294.3 W kg−1 in H2SO4. While in Na2SO4, the energy density achieves 72.6 W h Kg−1 at a power density of 217.7 W kg−1 and 13.3 W h Kg−1 at power density of 3993.8 W kg−1, respectively. The composite also presents good cycling stability (86.6, 73.4% at 20 mV s−1 after 200 cycles in 1 M H2SO4 and Na2SO4, respectively).
Co-reporter:Jin Li, Xiaoheng Liu, Qiaofeng Han, Xiaxi Yao and Xin Wang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 4) pp:NaN1253-1253
Publication Date(Web):2012/11/08
DOI:10.1039/C2TA00382A
Self-assembly can offer a very powerful tool for the design of novel materials and many different templates have been found to direct the formation of microstructures. In this article, we report a simple method for the self-assembly of three-dimensional (3D) WO3 nanotube bundles. It is demonstrated that not only can NaHSO4 act as a reactant, but also, more importantly, it played multiple key roles in the self-assembly processes, while NH4HSO4 and KHSO4 have none of these functions at all. As suggested, at first, WO3 ordered and layered structures can be generated by the hydrothermal reaction of NaHSO4 with Na2WO4 at 180 °C, and then sodium ions (Na+) inserted into the layer cause a continual curl of the WO3 outer-slice by the repel force of static electricity between Na+ ions and H+ ions on the surface of the WO3 slice. Herein, Na+ ions can dramatically promote the formation of WO3 single crystal slices, which are precursors of the self-assembly, and SO42− ions can bridge the WO3 slices as well as the nanotubes. In addition, it is found that the WO3 nanotube bundles still keep their original aggregation after template removal, and the bundle can be disassembled gradually under a long treatment time of aqueous ultrasonication. Furthermore, the application in wastewater treatment of WO3 nanotube bundles has been investigated.
Co-reporter:Huajie Huang and Xin Wang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 18) pp:NaN6291-6291
Publication Date(Web):2014/01/06
DOI:10.1039/C3TA14754A
With the continuously increasing demand of energy along with depletion of conventional fossil fuel reserves and the rapidly escalating environmental problems, direct methanol fuel cells (DMFCs) as alternative green and sustainable power sources have aroused tremendous research interest in academic and engineering circles. In order to achieve high power density as well as low production cost of DMFCs, the well-designed and fabricated anode catalysts with controllable composition, architecture and morphology have been regarded as a key point for realizing high-performance. In this aspect, carbon materials, as building blocks, offer a great potential to play a key role in constructing advanced hybrid catalysts due to their exceptional physicochemical properties, such as high specific surface area, superior electronic conductivity, excellent stability and so on. This review summarizes the recent significant progress in the design and fabrication of novel carbon-based anode catalysts via various strategies and their applications in methanol oxidation reaction. Finally, perspectives on the challenges and research trends in this emerging area are also discussed.
Co-reporter:Huajie Huang, Gonglan Ye, Shubin Yang, Huilong Fei, Chandra Sekhar Tiwary, Yongji Gong, Robert Vajtai, James M. Tour, Xin Wang and Pulickel M. Ajayan
Journal of Materials Chemistry A 2015 - vol. 3(Issue 39) pp:NaN19701-19701
Publication Date(Web):2015/09/08
DOI:10.1039/C5TA05372B
The design and construction of nanostructured electrode catalysts with high activity at low cost are crucial elements in fuel cell technologies. Here, we demonstrate a combined hydrothermal self-assembly, freeze-drying, and thermal annealing approach for the fabrication of a hybrid catalyst made from nanosized Pt particles and three-dimensional (3D) nitrogen-doped graphene nanoribbons (N-GNRs). The resulting 3D architecture possesses a large surface area, interconnected porous networks, uniform nitrogen distribution, extremely small sizes of Pt NPs and good electrical conductivity, which are highly desirable for electrocatalysis of the methanol oxidation reaction. As a consequence, remarkable electrocatalytic properties including exceptional electrocatalytic activity, strong poison tolerance as well as superior long-term stability are achieved for the Pt/N-GNR architecture, all of which outperform those observed for Pt/Vulcan XC-72 (Pt/C), Pt/carbon nanotube (Pt/CNT) and Pt/undoped GNR (Pt/GNR) catalysts.
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