Co-reporter:Hui Xu, Ke Zhang, Bo Yan, Jin Wang, Caiqin Wang, Shumin Li, Zhulan Gu, Yukou Du, Ping Yang
Journal of Power Sources 2017 Volume 356(Volume 356) pp:
Publication Date(Web):15 July 2017
DOI:10.1016/j.jpowsour.2017.04.070
•The ultrasmall PdBi nanodots have been designed by a facile wet-chemical method.•The composition of PdBi nanodots can be easily controlled.•Mechanisms of formation have been explored.•The morphologies of PdBi nanocomposites is time-depended.•The obtained PdBi nanodots show superior electrocatalytic performances.Tuning the morphology and compositions of catalyst is an effective method for promoting electrocatalytic intrinsic activity. However, many newly-generated nanocrystals with better nanostructures often have a large size, which enforces them to display extremely limited surface area and ultimately lead to the limited electrocatalytic activity. To break this bottleneck, we herein report a facile and reproducible wet-chemical method to control the synthesis of a class of ultra-uniform and small PdBi nanodots endowed with both high surface areas and tunable compositions. The presented PdBi nanodots show the ultrasmall size (ca.2.5 nm) and great uniform dispersion property. These significant characteristics enable them to exhibit unprecedented electrocatalytic activities and durability toward formic acid oxidation. The mass activity and electrochemical surface active (ECSA) of prepared PdBi nanodots for the formic acid oxidation is 8.9/3.75 times higher than that of commercial Pd/C, respectively. We speculate that both of this facile synthetic approach and remarkable electrocatalytic performance of the obtained catalysts in this work illustrate that they can be applied as a promising catalyst for direct formic acid cells.Download high-res image (428KB)Download full-size image
Co-reporter:Hui Xu, Bo Yan, Ke Zhang, Caiqin Wang, Jiatai Zhong, Shumin Li, Yukou Du, Ping Yang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017 Volume 522(Volume 522) pp:
Publication Date(Web):5 June 2017
DOI:10.1016/j.colsurfa.2017.03.015
•Effects of different solvents on the formations of PdAu NNs have been studied.•The interactions between PdAu NNs and different solvents are also investigated.•Polarity and functional groups of solvent affect the properties of PdAu NNs.•The prepared PdAu NNs show superior catalytic activity for EG and isopropanol oxidation.Solvents play a key role in controlling the fabrication and modification of nanoparticles. We herein demonstrated that the dispersibility, stability, morphology and structure of PdAu nanoparticles varied with the polarity, special functional groups and self-properties of solvents. The underlying causes for solvent dependence were attributed to the interactions between the solvent and PdAu nanoparticles coated with PVP. Additionally, in comparison with commercial Pd/C, the obtained PdAu nanowire networks prepared in different solvents exerted considerable high electrocatalytic activity and stability towards ethylene glycol and isopropanol electrooxidation, particular for the PdAu nanowire networks prepared in DMF, which exhibited the well-dispersed nanowire network structure with large quantity of surface active areas, superior electrocatalytic activity together with long-term stability. Our efforts not only highlighted the facile preparations of the effective PdAu nanowire networks for the potential anodic catalysts for the application of fuel cells, but also facilitated the selections of appropriate solvents for preparing valid catalysts.Download high-res image (195KB)Download full-size image
Co-reporter:Yijie Wu, Zongkuan Yue, Aijuan Liu, Ping Yang, and Mingshan Zhu
ACS Sustainable Chemistry & Engineering 2016 Volume 4(Issue 5) pp:2569
Publication Date(Web):April 6, 2016
DOI:10.1021/acssuschemeng.5b01795
By doping Cu(I) ions in Zn0.3Cd0.7S, a novel p-type Cu doped Zn0.3Cd0.7S modified graphene (Zn0.3Cd0.7S (Cu)/GR) film photocathode was prepared. The as-prepared p-type Zn0.3Cd0.7S (Cu)/GR photocathode and an n-type WO3/graphene (WO3/GR) photoanode were used to assemble a photoelectrochemical tandem cell. Through examination of the optoelectronic and photoelectrochemical properties of Zn0.3Cd0.7S (Cu)/GR and WO3/GR photoelectrode, we evaluate the feasibility of the tandem cell for overall water splitting under UV–vis light irradiation. The optimal Cu doping in Zn0.3Cd0.7S photocathode concentration was found to be 6%. The rates of hydrogen and oxygen evolved from this tandem cell with the optimal electrodes were 65.6 and 12.3 μmol g–1 h–1 (80.5 and 15.1 μmol cm–2 h–1), respectively. This study suggests a promising method for constructing an efficient photoelectrochemical tandem device for overall water splitting.Keywords: Cu-doped Zn0.3Cd0.7S; Overall water splitting; Photoelectrochemical tandem cell;
Co-reporter:Bin Xiao, Mingshan Zhu, Xia Li, Ping Yang, Liqun Qiu, Cheng Lu
International Journal of Hydrogen Energy 2016 Volume 41(Issue 27) pp:11537-11546
Publication Date(Web):20 July 2016
DOI:10.1016/j.ijhydene.2015.11.166
•Covalently linked silicon-phthalocyanine-graphene nanocomposite was synthesized.•SiPc(phenyl)2G2/Pt worked as efficient photocatalyst for H2 production.•Surfactant improved the stability and activity of the photocatalytic H2 evolution.A new hybrid silicon-phthalocyanine phenyl covalently functionalized graphene (SiPc(phenyl)2G2) was synthesized. The high fluorescence quenching efficiency and enhanced photocurrent suggested a rapid photoinduced energy transfer from SiPc(phenyl) moiety to graphene sheets through the covalent bond. Using the above synthesized hybrid as a photosensitizer, the SiPc(phenyl)2G2 functionalized Pt nanocomposite (SiPc(phenyl)2G2/Pt) was easily obtained via photodeposition method. The as-prepared SiPc(phenyl)2G2/Pt showed efficient photocatalytic hydrogen generation from water splitting under both UV–vis and visible light irradiation. Interestingly, with the aid of surfactants, the photocatalytic activity and stability of the SiPc(phenyl)2G2/Pt nanocomposites in the solution were distinctly improved owning to the nanocomposite aggregation prevention. This investigation demonstrates a unique approach to construct stable high photoresponisve organic hybrid composites for solar energy utilization.
Co-reporter:Dandan Wang, Jie Huang, Kezhen Li, Chunyong Zhang, Yukou Du and Ping Yang
RSC Advances 2016 vol. 6(Issue 41) pp:34699-34707
Publication Date(Web):30 Mar 2016
DOI:10.1039/C6RA03542F
In this paper, a novel nanohybrid composed of cis-dithiocyanato-bis(2,2′-bipyridine-4,4′-dicarboxylate)ruthenium(II) (N3) covalently functionalized reduced graphene oxide (N3-RGO) has been synthesized. The nanocomposite is characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), fluorescence, and UV-vis spectroscopy. The results demonstrate that the N3 dye molecules have been covalently grafted on the graphene sheets. The efficient fluorescence quenching and the enhanced photocurrent response confirm that the photoinduced electron transfer from the N3 moiety to the graphene sheet and charge recombination have been suppressed. Platinum nanoparticles as cocatalysts loaded on the N3-RGO nanosheets show a remarkable improvement in photocatalytic hydrogen evolution. The amount of hydrogen evolved from N3-RGO/Pt reached 11.25 and 1.78 μmol mg−1 under 7 h of UV-vis and visible light irradiation, respectively. This work provides a new way to design more efficient graphene-based nanocomposite photocatalysts for solar energy conversion.
Co-reporter:Dandan Wang, Jie Huang, Xia Li, Ping Yang, Yukou Du, Cynthia M. Goh and Cheng Lu
Journal of Materials Chemistry A 2015 vol. 3(Issue 8) pp:4195-4202
Publication Date(Web):16 Dec 2014
DOI:10.1039/C4TA05721J
In this paper, a manganese phthalocyanine (MnPc) covalently functionalized graphene nanohybrid (MnPcG) has been successfully synthesized via 1,3-dipolar cycloaddition, and used as a photocatalyst after modifying it with platinum nanoparticles via photodeposition. The nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis, Fourier transform infrared (FTIR), and Raman spectroscopy. These characterization results confirmed the grafting of MnPc moiety onto the graphene sheets. The intermolecular electron transfer was facilitated and the photoexcited charges recombination was suppressed as confirmed by the fluorescence quenching and enhanced photocurrent density in MnPcG nanohybrid. In comparison to graphene, the MnPcG nanohybrid shows a substantial improvement in the photocatalytic hydrogen evolution. The yields of hydrogen production of MnPcG/Pt reached to 8.59 and 1.45 μmol mg−1 under 10 h of UV-vis and visible light (λ > 400 nm) irradiation, respectively. This work demonstrates that metallophthalocyanines covalently functionalized graphene is a novel photocatalyst for solar energy conversion to produce hydrogen from water.
Co-reporter:Jie Huang, Yijie Wu, Dandan Wang, Yufei Ma, Zongkuan Yue, Yongtao Lu, Mengxin Zhang, Zhijun Zhang, and Ping Yang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 6) pp:3732
Publication Date(Web):January 23, 2015
DOI:10.1021/am508476d
To improve the photocatalytic activity of graphene-based catalysts, silicon phthalocyanine (SiPc) covalently functionalized N-doped ultrasmall reduced graphene oxide (N-usRGO) has been synthesized through 1,3-dipolar cycloaddition of azomethine ylides. The obtained product (N-usRGO/SiPc) was characterized by transmission electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, Raman spectra, X-ray photoelectron spectroscopy, fluorescence, and UV–vis spectroscopy. The results demonstrate that SiPc has been successfully grafted on the surface of N-usRGO. The N-usRGO/SiPc nanocomposite exhibits high light-harvesting efficiency covering a range of wavelengths from the ultraviolet to visible light. The efficient fluorescence quenching and the enhanced photocurrent response confirm that the photoinduced electron transfers from the SiPc moiety to the N-usRGO sheet. Moreover, we chose Pt nanoparticles as cocatalyst to load on N-usRGO/SiPc sheets to obtain the optimal H2 production effect. The platinized N-usRGO/SiPc (N-usRGO/SiPc/Pt) demonstrates good hydrogen evolution performance under both UV–vis and visible light (λ>400 nm) irradiation. The apparent quantum yields are 1.3% and 0.56% at 365 and 420 nm, respectively. These results reveal that N-usRGO/SiPc/Pt nanocomposite, consolidating the advantages of SiPc, N-usRGO, and Pt NPs, can be a potential candidate for hydrogen evolution from water under UV–vis or visible light irradiation.Keywords: hydrogen evolution; N-doped ultrasmall graphene; photocatalysis; silicon phthalocyanine
Co-reporter:Yijie Wu, Dongmei Chu, Ping Yang, Yukou Du and Cheng Lu
Catalysis Science & Technology 2015 vol. 5(Issue 6) pp:3375-3382
Publication Date(Web):24 Apr 2015
DOI:10.1039/C5CY00439J
A novel ternary nanocomposite comprising mesoporous WO3, Mn3O4 nanoparticles and N-doped graphene was prepared by a one-pot deposition method. The nanocomposite was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The results demonstrated that the Mn3O4 nanoparticles had been successfully hybridized with the mesoporous WO3 and the WO3/Mn3O4 hybrid was well dispersed on the surface of N-doped graphene with superior interactions. The nanocomposite exhibits higher photocatalytic activity for water oxidation than the individual mesoporous WO3 and WO3/Mn3O4 catalysts. The amount of oxygen evolution from the optimized heterostructural photocatalyst (1.5 wt% Mn3O4 and 2 wt% N-doped graphene) was 294 μmol g−1, which was about 3.6 times as high as that from m-WO3. The heterostructure formed between Mn3O4 and m-WO3 enhances photogenerated electron/hole transfer and restrains the recombination of charges greatly. N-doped graphene in the nanocomposite acting as an excellent electron acceptor and mediator also contributes to the increase in photocatalytic performance by promoting the separation and transfer of photogenerated charges. This study suggests a promising method to enhance photocatalytic activity by combining the heterostructural WO3/Mn3O4 hybrid with graphene in a ternary system.
Co-reporter:Yongtao Lu, Dongmei Chu, Mingshan Zhu, Yukou Du and Ping Yang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 26) pp:17355-17361
Publication Date(Web):27 May 2015
DOI:10.1039/C5CP01657F
A binary composite composed of two dimensional (2D) ultrathin carbon nitride (C3N4) nanosheets and NiS nanoparticles was synthesized and applied as a noble-metal-free photocatalyst for hydrogen evolution under visible light irradiation. The ultrathin nanosheets of C3N4 were obtained by a facile liquid exfoliation method and used as 2D supports for the deposition of NiS nanoparticles. In the binary composite, the ultrathin C3N4 nanosheets acted as a visible light responding semiconductor, and the NiS nanoparticles served as a noble-metal-free cocatalyst. The binary composite with an optimized composition gave a hydrogen evolution rate comparable to that of Pt modified C3N4. Moreover, compared to bulk C3N4, the exfoliated C3N4 nanosheets distinctly improve the photocatalytic performance for hydrogen evolution. The photocatalytic results combined with photoelectrochemical experiments show that C3N4 with an ultrathin structure promotes the electron–hole separation and transportation during the process of the photoinduced hydrogen evolution. This study displays a facile method to build a low-cost but effective photocatalyst for hydrogen production under visible light irradiation.
Co-reporter:Jie Huang
The Journal of Physical Chemistry C 2015 Volume 119(Issue 50) pp:27892-27899
Publication Date(Web):November 18, 2015
DOI:10.1021/acs.jpcc.5b09483
To improve the photocatalytic activity of graphene-based catalysts, an efficient photocatalytic hydrogen evolution system based on black dye N749 covalently functionalized reduced graphene oxide (rGO-N749) was synthesized. The obtained product was characterized with transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), Raman spectra, X-ray photoelectron spectroscopy (XPS), and fluorescence and UV–vis spectroscopy. The results demonstrate that N749 has been successfully grafted on the surface of rGO. The rGO-N749 nanocomposite exhibits high light-harvesting efficiency and covered a range of wavelengths from the ultraviolet to visible light. The efficient fluorescence quenching and the enhanced photocurrent response confirm that the photoinduced electron transfers from the N749 moiety to the rGO sheet. Moreover, we chose Pt nanoparticles (NPs) as cocatalyst loading on rGO-N749 sheets to obtain the optimal H2 production effect. The platinized rGO-N749 (rGO-N749-Pt) demonstrates a quite high photocatalytic activity for hydrogen evolution from water under both UV–vis and visible light (λ > 400 nm) irradiation. The apparent quantum yields are 0.54 and 0.21% at 365 and 420 nm, respectively. These results reveal that the rGO-N749-Pt nanocomposite consolidated the advantages of N749, rGO, and Pt NPs and can be a potential candidate for hydrogen evolution from water under UV–vis or visible-light irradiation.
Co-reporter:Hui Huang, Chao Wang, Jie Huang, Xiaomei Wang, Yukou Du and Ping Yang
Nanoscale 2014 vol. 6(Issue 13) pp:7274-7280
Publication Date(Web):09 Apr 2014
DOI:10.1039/C4NR00505H
Highly ordered N-doped mesoporous niobium oxide (NMNb) was prepared via a facile solid state reaction method using urea as a nitrogen source. The mesoporous structure of niobium oxide (MNb) is beneficial to the N dopant that is effectively incorporated into the lattice of MNb, resulting in a significantly enhanced visible light response. The hydrogen generation efficiency over the optimized N-doped MNb photocatalyst was 14.8 times as high as that from N-P25 under 5 h visible light irradiation. The improved photocatalytic activity of NMNb was mainly due to the fact that the inherited ordered mesostructure of NMNb could offer more active sites for the photocatalytic reaction, as well as accelerate the photogenerated electron–hole pair transfer and separation.
Co-reporter:Hui Huang, Zongkuan Yue, Gang Li, Xiaomei Wang, Jie Huang, Yukou Du and Ping Yang
Journal of Materials Chemistry A 2014 vol. 2(Issue 47) pp:20118-20125
Publication Date(Web):2014/10/06
DOI:10.1039/C4TA04106B
A novel composite of In2O3 nanorods (INR) hybridized with reduced graphene oxide (RGO) was fabricated by a facile UV-assisted photoreduction method. The as-prepared samples were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The one-dimensional INR with high surface-to-volume ratio anchored on the surface of RGO homogeneously, resulting in a nice interfacial contact between INR and RGO. The photocatalytic activities of the INR–RGO composites were investigated for 4-chlorophenol (4-CP) degradation under UV-vis or visible light irradiation. The photodegradation yield of the optimized photocatalyst reached 91.6%, which was about 1.9 times as high as that of INR under visible light irradiation (>400 nm). The enhanced photocatalytic activity of the INR–RGO composites can be ascribed to the efficient interfacial charge transfer from INR to RGO, which resulted in the prolonged lifetime of the photoinduced charge carriers.
Co-reporter:Zhigang Mou, Yijie Wu, Jianhua Sun, Ping Yang, Yukou Du, and Cheng Lu
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 16) pp:13798
Publication Date(Web):July 31, 2014
DOI:10.1021/am503244w
Titanium dioxide (TiO2) nanoparticles-functionalized N-doped graphene (NGR) composites (NGR/TiO2) were prepared through solvothermal treatment approach using exfoliated NGR and tetrabutyl titanate as the staring materials. The composites were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra, photoelectrochemical, and electrochemical measurements. Nitrogen doping provides favorable nucleation and anchor sites for TiO2 nanocrystals formation on NGR sheets, helping to form an intimate interfacial contact between NGR and TiO2 nanoparticles. Moreover, NGR has higher electrical conductivity than the reduced graphene oxide (RGO) due to the recovery of the sp2 graphite network and decrease of defects, resulting in more effective charge transfer and charge separation in the NGR/TiO2 composite. NGR/TiO2 nanocomposite demonstrated a higher photocatalytic activity for hydrogen production as compared to its counterpart, TiO2-functionalized RGO composite (RGO/TiO2). This work provides new insights to design new more efficient graphene-based nanocomposite photocatalysts for solar energy conversion.Keywords: hydrogen generation; N-doped graphene; nanocomposite photocatalyst; platinum; TiO2
Co-reporter:Yongtao Lu, Dandan Wang, Ping Yang, Yukou Du and Cheng Lu
Catalysis Science & Technology 2014 vol. 4(Issue 8) pp:2650-2657
Publication Date(Web):17 Apr 2014
DOI:10.1039/C4CY00331D
A novel nanocomposite composed of two-dimensional graphene-like MoS2 and ZnxCd1−xS (0 ≤ x ≤ 0.5) nanoparticles has been synthesized by a simple exfoliation of bulk MoS2 into single- or few-layer MoS2 and then ultrasonic mixing of ZnxCd1−xS onto MoS2 nanosheets. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), photoelectrochemical experiments and photoluminescence spectroscopy. The results show that the nanoparticles of ZnxCd1−xS are well dispersed and anchored on the surface of the graphene-like MoS2 nanosheets. The superior interfacial coupling between ZnxCd1−xS and MoS2 synergistically promoted the electron–hole transportation and separation. Upon visible-light irradiation (λ > 420 nm), the composite consisted of Zn0.3Cd0.7S and ca. 0.6 wt% graphene-like MoS2 gave the highest hydrogen evolution amount of 7179.1 μmol g−1, which is ca. 7 times as high as that of Zn0.3Cd0.7S. This study shows a facile method to build a low-cost but effective photocatalyst for water reduction to produce hydrogen under solar light irradiation.
Co-reporter:Shunli Yin, Xiaomei Wang, Zhigang Mou, Yijie Wu, Hui Huang, Mingshan Zhu, Yukou Du and Ping Yang
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 23) pp:11289-11296
Publication Date(Web):11 Mar 2014
DOI:10.1039/C4CP00384E
A novel nanocomposite consisting of α-Fe2O3, Mn3O4 and reduced graphene oxide (r-GO) has been facilely synthesized through a two-step method: solvothermal reaction for Mn3O4-modified α-Fe2O3 (α-Fe2O3/Mn3O4) and self-assembly process for combining α-Fe2O3/Mn3O4 with r-GO (α-Fe2O3/Mn3O4/r-GO). The morphology and structure of the nanocomposite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that rod-like hematite was modified by Mn3O4 and dispersed on the surface of r-GO. Raman and Fourier transform infrared spectra (FTIR) showed superior interfacial contacts between α-Fe2O3/Mn3O4 and r-GO. Ultraviolet-visible diffuse reflectance spectroscopy (DRS) and photoelectrochemical characterization revealed a high light-harvesting efficiency, a lowered overpotential for water oxidation and an excellent charge transfer performance of α-Fe2O3/Mn3O4/r-GO nanocomposite with heterostructures. The photocatalytic oxygen evolution from the optimized photocatalyst was up to 1406.2 μmol g−1 in 10 h of UV-vis light irradiation and the quantum yield was ca. 4.35% at 365 nm. Our investigation suggests that constructing a catalyst with heterostructures is a promising method to enhance photocatalytic activity.
Co-reporter:Yongtao Lu, Dandan Wang, Zhigang Mou, Jie Huang, Yukou Du, Ping Yang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 457() pp:282-287
Publication Date(Web):5 September 2014
DOI:10.1016/j.colsurfa.2014.05.069
•A multibranched triphenylamine dye functionalized Pt nanocomposite was synthesized.•The multibranched triphenylamine dye demonstrated effective light-absorption.•Efficient electron transfer from the dye to Pt enhanced the photocatalytic activity.A multibranched triphenylamine-based dye (tris(4-(2-(2-(pyridin-2-yl))-carbonyl-vinyl-)phenyl)amine) functionalized platinum homogeneous catalyst was successfully synthesized and characterized by Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet–visible absorption (UV–vis), and fluorescence studies. The FT-IR, TEM, and XRD studies demonstrated that the as-prepared homogeneous catalyst could be described as an organic-inorganic nanosphere composed of an organic multibranched dye shell and a platinum nanocore (ca. 2.9 nm). The fluorescence quenching and fluorescence decay studies indicated that the interfacial electrons transferred directly from the dye molecule to the platinum nanoparticle in this homogeneous catalyst under light irradiation. The homogeneous catalyst could be used as a stable photocatalyst for homogeneous photoinduced hydrogen evolution without an electron relay under UV–vis light irradiation.Efficient photo-excited electron transfer from the dye-shell to the platinum-core in the photocatalytic splitting of water under UV–vis light irradiation.
Co-reporter:Hui Huang, Zongkuan Yue, Gang Li, Xiaomei Wang, Jie Huang, Yukou Du and Ping Yang
Journal of Materials Chemistry A 2013 vol. 1(Issue 47) pp:15110-15116
Publication Date(Web):11 Oct 2013
DOI:10.1039/C3TA13433D
In this paper, we report the synthesis, characterization, and photocatalysis of a novel composite, composed of high-ordered mesoporous WO3 (m-WO3) and reduced graphene oxide (RGO). The composite was systematically characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, N2 adsorption–desorption and UV-visible diffuse reflectance spectroscopy techniques. The superior contact between two moieties in the composites facilitates the charge carrier separation and the evolution of oxygen. Under visible light irradiation, the amount of oxygen evolution from the optimized photocatalyst containing ca. 6 wt% RGO reached 437.3 μmol g−1, which was 5.1 times as high as that from m-WO3. The enhancement of photocatalytic activity could be ascribed to the fact that RGO acts herein as a solid-state electron mediator, promoting the charge transportation and separation, as well as suppressing the electron–hole recombination in the composite. This study might provide a prototype for constructing a novel photocatalytic system by hybridizing graphene with a mesoporous semiconductor for solar energy conversion.
Co-reporter:Mingshan Zhu, Zhi Li, Bin Xiao, Yongtao Lu, Yukou Du, Ping Yang, and Xiaomei Wang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 5) pp:1732
Publication Date(Web):February 5, 2013
DOI:10.1021/am302912v
In this paper, a 5,10,15,20-tetrakis(4-(hydroxyl)phenyl) porphyrin (TPPH) noncovalently functionalized reduced graphene oxide (RGO) nanohybrid has been facilely synthesized by immobilizing TPPH on RGO nanosheets. This nanohybrid was characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), and UV–vis spectra, which demonstrated that the TPPH molecule was attached on the surface of the graphene nanosheet. The results of fluorescence quenching and photocurrent enhancement of TPPH–RGO exhibit that the fast electrons transfer from photoexcited TPPH molecules to RGO sheets. Compared with bare TPPH or RGO functional Pt nanoparticles, the TPPH-sensitized RGO loaded with Pt nanoparticles shows remarkable enhanced photocatalytic activity under UV–vis light irradiation. The superior electron-accepting and electron-transporting properties of graphene greatly accelerate the electron transfer from excited TPPH to Pt catalysts, which promote the photocatalytic activity for hydrogen evolution. More importantly, with the assistance of cetyltrimethylammonium bromide (CTAB) surfactant, the catalytic activity and stability is further improved owing to aggregation prevention of TPPH–RGO nanocomposites. Our investigation might not only initiate new opportunities for the development of a facile synthesis yet highly efficient photoinduced hydrogen evolution system (composed of organic dye functionalized graphene) but also pave a new avenue for constructing graphene-based matericals with enhanced catalytic performance and stability under surfactant assistance.Keywords: electron transfer; hydrogen evolution; noncovalently functionalized graphene; photocatalysis; porphyrin; surfactant;
Co-reporter:Mingshan Zhu, Yukou Du, Ping Yang and Xiaomei Wang
Catalysis Science & Technology 2013 vol. 3(Issue 9) pp:2295-2302
Publication Date(Web):21 May 2013
DOI:10.1039/C3CY00236E
In this paper, a novel porphyrin dye (5,10,15,20-tetrakis (4-(anthracene-1-ylmethoxy)phenyl) porphyrin, TPPAN) and its functionalized platinum nanoparticles (Pt-TPPAN) were synthesized. Using the Pt-TPPAN nanocomposite as a photocatalyst, a new and more compact photoinduced hydrogen evolution system from an aqueous ethanol solution without additives was developed. Fluorescence and photo-electrochemical spectra reveal that photoinduced electron transfer occurs from the photoexcited state of anthracene substituents to the porphyrin, accompanied by an electron transfer from the excited porphyrin moiety to the Pt co-catalyst. The photocatalytic activity results suggested that this TPPAN functionalized Pt nano-assembly could efficiently catalyze hydrogen evolution from an aqueous ethanol solution under simulated solar light irradiation. Therein, the TPPAN molecule in the nanocomposite worked as a light absorption antenna and the nanocore Pt species acted as a co-catalyst. This investigation might offer a new paradigm for constructing a simpler and more efficient homogeneous photocatalytic hydrogen evolution system for mimicking natural photosynthesis.
Co-reporter:Zhigang Mou, Shunli Yin, Mingshan Zhu, Yukou Du, Xiaomei Wang, Ping Yang, Junwei Zheng and Cheng Lu
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 8) pp:2793-2799
Publication Date(Web):14 Dec 2012
DOI:10.1039/C2CP44270A
A novel composite composed of TiSi2, graphene and RuO2 nanoparticles was fabricated by a one-pot deposition method using reduced graphene oxide (RGO) as a supporting matrix and RuCl3 as the RuO2 precursor. The resulting RuO2/TiSi2/RGO composite was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectra, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectra, photoelectrical response and electrochemical impedance spectra. The results indicated that the three components in the composite were effectively contacted, thus facilitating the photogenerated charges transfer and separation through multiple routes. By using the composite as a photocatalyst for visible-light water splitting the average hydrogen production rate could reach 97.5 μmol h−1 g−1, which is higher than that from RuO2/TiSi2 and pure TiSi2 systems under the same conditions.
Co-reporter:Manhuan Cheng, Mingshan Zhu, Yukou Du, Ping Yang
International Journal of Hydrogen Energy 2013 Volume 38(Issue 21) pp:8631-8638
Publication Date(Web):17 July 2013
DOI:10.1016/j.ijhydene.2013.05.040
•Au@Pt-TPAD is facile obtained by depositing Pt atoms on the surface of Au seed.•TPAD molecule in the Au@Pt-TPAD hybrid acts both as stabilizer and photosensitizer.•Photoelectron can efficiently transfer from TPAD molecule to the bimetallic nanoparticle.•Au@Pt-TPAD photocatalyst exhibits efficient and stable hydrogen evolution activity.An efficient photocatalytic hydrogen evolution system based on triphenylamine-based dye functionalized bimetallic Au@Pt core/shell nanocomposite (Au@Pt-TPAD) was reported. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV–vis absorption spectra suggested that Au@Pt-TPAD nanocomposite consisted of a bimetallic nanoparticle with Au core and Pt shell nanostructure. The photoelectrochemical result suggested that photoinduced electrons could efficiently transfer from the triphenylamine derivative molecules to the bimetallic nanoparticles. Photocatalytic results showed that the Au@Pt2-TPAD bimetallic nanocomposite could be used as a stable photoinduced H2 evolution photocatalyst. Compared with the monometallic counterpart (Au-TPAD or Pt-TPAD), the bimetallic nanocomposite showed much higher catalytic activity for the photocatalytic hydrogen evolution. The amount of hydrogen evolution on the optimal catalyst under 12 h UV–vis light irradiation was about 37.5 μmol. The enhancement of the photocatalytic activity might be attributed to the synergistic effect between the two metals in bimetallic nanoparticles with core/shell structure. This investigation might open up new opportunities for the development of dye functionalized heterometallic nanocomposite with enhanced photocatalytic performance.
Co-reporter:Zhangquan Yao, Ruirui Yue, Chunyang Zhai, Fengxing Jiang, Huiwen Wang, Yukou Du, Chuangyi Wang, Ping Yang
International Journal of Hydrogen Energy 2013 Volume 38(Issue 15) pp:6368-6376
Publication Date(Web):20 May 2013
DOI:10.1016/j.ijhydene.2013.02.140
•Electrochemical fabrication of N–Pt/RGO/CF electrode.•Large surface area and unique three-dimensional pore structure.•Enhanced catalytic activity and stability toward methanol electrooxidation.Here, we report a novel method for assembling reduced graphene oxide (RGO) and Pt nanoparticles on a carbon fiber (CF) electrode successively to form a stable Pt nanoparticle-RGO-Pt nanoparticle-RGO/CF multiple junction for electrocatalysis application. As the SEM imaging exhibited, Pt nanoparticles are uniformly deposited on the surface of each RGO sheet, performing an alternative covering structure of RGO and Pt nanoparticle multi-layer on the CF electrode. Thus, a novel three-dimensional (3D) multi-layered Pt/RGO modified CF electrode (N–Pt/RGO/CF) is obtained. Experimental results demonstrate that the prepared N–Pt/RGO/CF electrode shows good electrochemical properties and enhanced electrocatalytic activity toward methanol electrooxidation in alkaline medium as compared with the Pt/RGO/CF electrode without layer-by-layer structure or the Pt/CF electrode without RGO. It is due to the unique 3D pore structure of N–Pt/RGO/CF and the good electron transport property of RGO in the composite electrode.
Co-reporter:Yuejun Song;Lianyan Wang;Robert M. Wenslow Jr.;Bo Tan;Hailu Zhang;Zongwu Deng
Journal of Pharmaceutical Sciences 2013 Volume 102( Issue 6) pp:1915-1923
Publication Date(Web):
DOI:10.1002/jps.23538
Abstract
To improve the dissolution and hence the oral bioavailability, amorphous felodipine (FEL) solid dispersions (SDs) with Kollidon® VA 64 (PVP/VA) were prepared. Hot-melt extrusion was employed with an extruding temperature below the melting point (Tm) of FEL. X-ray powder diffraction (XRPD) and 13C CP/MAS nuclear magnetic resonance (NMR) measurements show that the extrudates are amorphous. The intermolecular interaction between FEL and PVP/VA in SDs was investigated by Fourier transform infrared spectroscopy, 15N CP/MAS NMR, and 1H high-resolution MAS NMR. Furthermore, a single glass transition temperature (Tg) was detected by differential scanning calorimetry in addition to a single 1H T1 or T1rho relaxation time detected by 13C NMR signals. These results confirm that the extrudates contain FEL dispersed into the polymer matrix at a molecular level with no detectable phase separation. This molecular-scale mixing results in a significantly faster dissolution rate compared with the pure crystalline FEL. Additionally, the molecular-scale mixing prevents the amorphous drug from recrystallizing even after being stored at 40°C/75% Relative Humidity for 2 months. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:1915–1923, 2013
Co-reporter:Yajing Chen, Zhigang Mou, Shunli Yin, Hui Huang, Ping Yang, Xiaomei Wang, Yukou Du
Materials Letters 2013 Volume 107() pp:31-34
Publication Date(Web):15 September 2013
DOI:10.1016/j.matlet.2013.05.065
•Designed and fabricated Ru(dcbpy)3-sensitized TiO2/graphene nanocomposite.•The nanocomposite shows nice photocatalytic activity for H2 evolution.•The electron–hole recombination was effectively restrained by grapheme.A novel graphene-based nanocomposite composed of tris(4,4′-dicarboxy-2,2′-bipyridine) ruthenium chloride (Ru(dcbpy)3) sensitized TiO2 and reduced graphene oxide (RGO) was prepared by a colloidal blending method and characterized by X-ray diffraction, high-resolution transmission electron microscopy, Raman spectroscopy and UV–vis diffuse reflectance spectroscopy. The nanocomposite demonstrated nice photocatalytic activity and stability for water reduction to produce hydrogen. The amount of H2 evolved from the optimized Ru(dcbpy)3/TiO2/RGO/Pt catalyst is 959 μmol g−1 at pH 3 under 5 h visible-light irradiation.
Co-reporter:Bin Xiao ; Xiaomei Wang ; Hui Huang ; Mingshan Zhu ; Ping Yang ; Yong Wang ;Yukou Du
The Journal of Physical Chemistry C 2013 Volume 117(Issue 41) pp:21303-21311
Publication Date(Web):September 20, 2013
DOI:10.1021/jp405497j
A novel nanohybrid composed of bipyridine ruthenium complex ((2,2′-bipyridyl)-4-pyridyl-chloro-ruthenium(II), Ru(bpy)2(py)Cl), covalently functionalized graphene (Ru(bpy)2(py)Cl/G), has been synthesized successfully via coordination of Ru(bpy)2Cl2 with pyridine covalently functionalized graphene (py/G), which was synthesized through 1,3-dipolar cycloaddition of azomethine ylides. Ru(bpy)2(py)Cl/G was characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra, Fourier transform infrared (FTIR), and ultraviolet–visible absorption (UV–vis). The fluorescence quenching efficiency of the nanohybrid excited at 290 and 535 nm was calculated to be 83% and 71%, respectively. The photocurrent density of the nanohybrid also significantly improved. The results revealed that fast photoinduced electron transfer from Ru(bpy)2(py)Cl moiety to graphene sheet occurred. Ru(bpy)2(py)Cl/G modified with platinum nanoparticles demonstrates remarkable enhanced photocatalytic activity for hydrogen evolution from water. Under 10 h UV–vis or visible light irradiation (>400 nm), the total amount of H2 evolution was 39.3 and 7.6 μmol mg–1, respectively. In addition, Ru(bpy)2(py)Cl/G/Pt nanohybrid shows sufficient stability for photocatalytic H2 evolution, and the hydrogen yield remains virtually unchanged in 50 h of irradiation. This study suggests that the carbon based nanohybrid composed of organic dye molecules covalently functionalized graphene is a promising candidate as a novel photocatalyst for photocatalytic hydrogen evolution.
Co-reporter:Zhigang Mou, Ming Han, Gang Li, Yukou Du, Ping Yang, Hailu Zhang, Zongwu Deng
Materials Research Bulletin 2013 48(11) pp: 4780-4784
Publication Date(Web):
DOI:10.1016/j.materresbull.2013.08.043
Co-reporter:Mingshan Zhu, Yupei Dong, Bin Xiao, Yukou Du, Ping Yang and Xiaomei Wang
Journal of Materials Chemistry A 2012 vol. 22(Issue 45) pp:23773-23779
Publication Date(Web):20 Sep 2012
DOI:10.1039/C2JM35322A
Herein, we report an efficient photocatalytic hydrogen evolution system based on Ru-tris(dicarboxybipyridine)–reduced graphene oxide (Ru(dcbpy)3–RGO) hybrid. AFM images and UV-vis spectra validate Ru(dcbpy)3 functionalized RGO via noncovalent interactions. Fluorescence and Raman spectra suggest that Ru(dcbpy)3 acts as an electron donor and RGO serves as an electron acceptor in the hybridized species. Moreover, the photocurrent experiment further confirms that the photoelectrons transfer from Ru(dcbpy)3 to RGO nanosheets and then flow to deposited Pt nanoparticles effectively. Compared with the corresponding single-component Ru(dcbpy)3 and RGO nanosheets, the Ru(dcbpy)3–RGO hybrid displays distinctly enhanced photocatalytic activities under UV-vis or visible light irradiation. Therein, RGO acts as a solid-state electron mediator, which facilitates charge separation and suppresses recombination of photoexcited electron–hole pairs in RGO–Ru(dcbpy)3. Furthermore, the effect of reaction parameters such as pH, the composition of the hybrid and the stability of catalytic performance are also investigated. This study might initiate new possibilities for the development of novel graphene-based photocatalysts with enhanced activity via facile noncovalent modification of graphene with organic photosensitizers.
Co-reporter:Zhangquan Yao, Mingshan Zhu, Fengxing Jiang, Yukou Du, Chuanyi Wang and Ping Yang
Journal of Materials Chemistry A 2012 vol. 22(Issue 27) pp:13707-13713
Publication Date(Web):10 May 2012
DOI:10.1039/C2JM31683H
In this paper, a facile electrochemical approach is developed towards synthesizing Pt nanoflowers modified reduced graphene oxide (RGO) wrapped carbon cloth (CC) as an anode (Pt nanoflowers/RGO/CCE) for formic acid and methanol electrooxidation. As revealed by SEM measurements, the carbon cloth is well wrapped by the RGO, and the RGO wrapped carbon cloth serves as an excellent support for electrochemically anchoring Pt nanoflowers, being more well-dispersed than without RGO. Compared with Pt nanoparticles/CCE, Pt nanoparticles/RGO/CCE, and Pt nanoflowers/CCE, the Pt nanoflowers/RGO/CCE displays a distinctly enhanced current density of CVs towards formic acid and methanol electrooxidation. The utilization of graphene results in well-dispersed Pt nanostructures with a uniform size and unique morphology structure; a relatively large surface area; and excellent electron or charge transfer rate, contributing to the enhanced electrocatalytic activity. The work likely opens up new promise for developing novel, low-cost yet highly efficient carbon material-based electrodes, especially for direct formic acid fuel cells and direct methanol fuel cells.
Co-reporter:Jun Zhong, Jiu-Jun Deng, Bao-Hua Mao, Tian Xie, Xu-Hui Sun, Zhi-Gang Mou, Cai-Hao Hong, Ping Yang, Sui-Dong Wang
Carbon 2012 Volume 50(Issue 1) pp:335-338
Publication Date(Web):January 2012
DOI:10.1016/j.carbon.2011.08.046
The evolution of solid state N-doping in graphene has been probed using X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectra show that the modification of graphene with N species can be achieved by urea attachment at annealing temperatures lower than 300 °C. A transition from urea to amino species is observed at 400 °C. At higher temperatures, pyridinic and graphitic type doping are achieved. The results indicate that the electronic structure of graphene can be controlled by solid state treatment, involving different N species depending on the annealing process.
Co-reporter:Zhi Li, Yajing Chen, Yukou Du, Xiaomei Wang, Ping Yang, Junwei Zheng
International Journal of Hydrogen Energy 2012 Volume 37(Issue 6) pp:4880-4888
Publication Date(Web):March 2012
DOI:10.1016/j.ijhydene.2011.12.045
A new type of graphene-based nanohybrid was prepared from graphene nanosheets and 4-(diphenylamino)benzaldehyde (TPA-CHO) through 1,3-dipolar cycloaddition. The nanohybrid was modified by platinum nanoparticles via photodeposition. The nanohybrid and its Pt modified nanocomposite were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Ultraviolet–visible absorption (UV–vis), Fourier transform infrared (FTIR), and Raman spectra confirmed that triphenylamine moiety grafted on the graphene surface. The results of fluorescence quenching and photocurrent enhancement of the triphenylamine-functionalized graphene revealed that photoinduced electron transfer from triphenylamine moiety to the graphene sheet. The investigation of using the Pt modified graphene-based nanocomposite as a photocatalyst for H2 evolution showed that under UV–vis light irradiation, the average H2 evolution rate and the quantum efficiency is 2.3 μmol h−1 and 0.45% mol E−1, respectively. This work demonstrated a potential application of an organic sensitizer covalently functionalized graphene as a novel photocatalyst in the field of solar energy conversion.Highlights► A novel nanocomposite composed of triphenylamine covalently functionalized graphene and Pt nanoparticles has been synthesized. ► Hydrogen evolution took place using the graphene-based nanocomposite as a photocatalyst under UV–vis light irradiation. ► The TPA moiety of G-TPA may harvest irradiation light and transfer photoinduced electrons to graphene, improving separation efficiency of carriers.
Co-reporter:Hui Huang, Zongkuan Yue, Yuejun Song, Yukou Du, Ping Yang
Materials Letters 2012 Volume 88() pp:57-60
Publication Date(Web):1 December 2012
DOI:10.1016/j.matlet.2012.08.018
Three-dimensionally ordered mesoporous WO3 was successfully synthesized by a hydrothermal method using mesoporous silica KIT-6 as a hard template and phosphotungstic acid as a precursor. The tungsten oxide after removal of silica template was characterized by powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Investigations of optical and photoelectrochemical properties showed that the mesoporous WO3 was a n-type semiconductor with a band gap of 2.6 eV and demonstrated prompt, steady, and reproducible photocurrent responses during repeated on/off cycles of visible light illumination (λ>420 nm). The mesoporous WO3 modified by platinum nanoparticles could be used as a stable photocatalyst for photoinducing O2 evolution. Under visible light irradiation, the average O2 evolution rate is 34.5 μmol g−1 h−1 in the presence of an electron acceptor IO3−. This work demonstrated a potential application of using mesoporous WO3 modified by platinum nanoparticles as a novel photocatalyst in the field of solar energy conversion.Highlights► Designed and fabricated ordered mesoporous WO3 catalysts with the cubic Ia3d symmetry structure. ► Mesoporous structured WO3 catalyst exhibits strong spectral response in the visible region. ► The higher photocatalytic activity is related primarily to large effective surface area and high ordered channel, resulting in low electron-hole recombination.
Co-reporter:Dr. Mingshan Zhu;Zhi Li;Dr. Yukou Du;Dr. Zhigang Mou;Dr. Ping Yang
ChemCatChem 2012 Volume 4( Issue 1) pp:112-117
Publication Date(Web):
DOI:10.1002/cctc.201100253
Abstract
Herein, 1,3,6,8-pyrenetetrasulfonic acid (PTSA) functionalized Pt nanocomposites were synthesized and characterized by UV/vis, X-ray photoelectron spectroscopic (XPS), FTIR, TEM, and XRD methods. Pyrenetetrasulfonic acid was not only used as the stabilizer to prevent agglomeration of Pt nanoparticles but also served as the light-harvesting photosensitizer, absorbing irradiating light and transferring photoexited electrons to the platinum nanoparticles. The occurrence of the photoinduced electron transfer process was confirmed by the combination of time-resolved fluorescence and photoelectrochemical spectral measurements. Photocatalytic results showed that PTSA functionalized Pt nanocomposites could be used as stable photocatalysts for photoinducing H2 evolution. At the optimal reaction conditions (nPt:nPTSA=100, pH 3), enhanced amounts of hydrogen were evolved from the system under UV/vis irradiation in the absence of an electron mediator. The corresponding amount of hydrogen evolution was 125.1 μmol for 12 h exposure to UV/vis irradiation, and the apparent quantum efficiency at a wavelength of λ=365 nm was 11.5 %.
Co-reporter:Dr. Mingshan Zhu;Yupei Dong;Dr. Yukou Du;Dr. Zhigang Mou;Jian Liu;Dr. Ping Yang;Dr. Xiaomei Wang
Chemistry - A European Journal 2012 Volume 18( Issue 14) pp:4367-4374
Publication Date(Web):
DOI:10.1002/chem.201102595
Abstract
Two donor–bridge–acceptor conjugates (5,10,15,20-tetrakis[4-(N,N-diphenylaminobenzoate)phenyl] porphyrin (TPPZ) and 5,10,15,20-tetrakis[4-(N,N-diphenylaminostyryl)phenyl] porphyrin (TPPX)) were covalently linked to triphenylamine (TPA) at the meso-position of porphyrin ring. The triphenylamine entities were expected to act as energy donors and the porphyrins to act as an energy acceptor. In this paper, we report on the synthesis of these multibranched-porphyrin-functionalized Pt nanocomposites. The conjugates used here not only served as a stabilizer to prevent agglomeration of Pt nanoparticles, but also as a light-harvesting photosensitizer. The occurrence of photoinduced electron-transfer processes was confirmed by time-resolved fluorescence and photoelectrochemical spectral measurements. The different efficiencies for energy and electron transfer in the two multibranched porphyrins and the functionalized Pt nanocomposites were attributed to diverse covalent linkages. Moreover, in the reduction of water to produce H2, the photocatalytic activity of the Pt nanocomposite functionalized by TPPX, in which the triphenylamine and porphyrin moieties are bonded through an ethylene bridge, was much higher than that of the platinum nanocomposite functionalized by TPPZ, in which the two moieties are bonded through an ester. This investigation demonstrates the fundamental advantages of constructing donor–bridge–acceptor conjugates as highly efficient photosensitizers based on efficient energy and electron transfer.
Co-reporter:Zhigang Mou, Xiaoye Chen, Yukou Du, Xiaomei Wang, Ping Yang, Suidong Wang
Applied Surface Science 2011 Volume 258(Issue 5) pp:1704-1710
Publication Date(Web):15 December 2011
DOI:10.1016/j.apsusc.2011.10.019
Abstract
Nitrogen doped graphene was synthesized from graphite oxide and urea by thermal solid-state reaction. The samples were characterized by transmission electron microscopy, atomic force microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectra, element analysis, and electrical conductivity measurement. The results reveal that there is a gradual thermal transformation of nitrogen bonding configurations from amide form nitrogen to pyrrolic, then to pyridinic, and finally to “graphitic” nitrogen in graphene sheets with increasing annealing temperature from 200 to 700 °C. The products prepared at 600 °C and 700 °C show that the quantity of nitrogen incorporated into graphene lattice is ∼10 at.% with simultaneous reduction of graphite oxide. Oxygen-containing functional groups in graphite oxide are responsible for the doping reaction to produce nitrogen doped graphene.
Co-reporter:Zhigang Mou, Yupei Dong, Shujin Li, Yukou Du, Xiaomei Wang, Ping Yang, Suidong Wang
International Journal of Hydrogen Energy 2011 Volume 36(Issue 15) pp:8885-8893
Publication Date(Web):July 2011
DOI:10.1016/j.ijhydene.2011.05.003
Chemically reduced graphene oxide (RGO) can be functionalized by eosin Y (EY). The formation of the stable aqueous EY functionalized graphene (EY-RGO) suspension is due to the non-covalent interaction between EY and RGO surface via hydrogen bonding and π–π stacking. EY-RGO was characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Spectral and photoelectrochemical studies indicate that photoinduced electron transfer occurs from EY to RGO. The EY-RGO is photocatalytic active for water reduction to produce hydrogen. The average production rate of H2 for the photocatalyst (wEY/wRGO = 1) in a 10 vol% triethanolamine aqueous solution can reach 3.35 mmol g−1 h−1 and 0.40 mmol g−1 h−1 under 30 h UV–vis and 10 h visible light irradiation, respectively. The photocatalytic activity of EY-RGO is superior to that of RGO, graphene oxide (GO), and EY-GO. Modification EY-RGO with Pt nanoparticles can further improve photocatalytic activity. All these features demonstrated that organic sensitizers functionalized graphene provided a nice candidate as a photocatalyst for H2 generation from water under solar light irradiation.Highlights► EY functionalized RGO extends light absorption into visible region. ► The photoinduced electron transfer occurs from EY to RGO. ► The photocatalytic activity of EY-RGO is superior to that of RGO, GO and EY-GO.
Co-reporter:Mingshan Zhu, Yongtao Lu, Yukou Du, Jian Li, Xiaomei Wang, Ping Yang
International Journal of Hydrogen Energy 2011 Volume 36(Issue 7) pp:4298-4304
Publication Date(Web):April 2011
DOI:10.1016/j.ijhydene.2011.01.007
A new system for photoinduced hydrogen production has been constructed using a porphyrin–pyrene conjugate functionalized Pt nanocomposite as a photocatalyst and ethylenediaminetetraacetic acid (EDTA) as a sacrificial reductant in the absence of an electron mediator. Detailed spectral, computational and photochemical studies reveal that a photoinduced energy transfer from the photoexcited state of pyrene to the porphyrin occurs, accompanied by an electron transfer from the excited porphyrin moiety to the platinum catalyst for the H2 generation. Efficient photocatalytic hydrogen evolution from the system demonstrates the possibility of constructing a photocatalytic system that uses a Pt nanocomposite functionalized by self-assembled donor–acceptor conjugates as a photocatalyst. The turnover numbers (TONPt and TONdye) and quantum yields of hydrogen (ΦH2ΦH2) for the photoinduced hydrogen production system are 63, 6311, and 2.65%, respectively, and are calculated on the basis that the total amount of H2 evolved after 12 h of irradiation.By using hydrogen bonding motif involving 5,10,15,20-tetrakis(4-(hydroxyl)phenyl)porphyrin and pyrenesulfonic acid, a conjugate with broader range of light absorption and efficient energy transfer from the pyrene to the porphyrin moiety has been constructed. It is found that the photocatalytic system that uses the conjugate functionalized Pt nanocomposite as a photocatalyst and EDTA as a sacrificial reductant is efficient for hydrogen evolution without an electron mediator.
Co-reporter:Ming Han;Hailu Zhang;Yukou Du
Reaction Kinetics, Mechanisms and Catalysis 2011 Volume 102( Issue 2) pp:393-404
Publication Date(Web):2011 April
DOI:10.1007/s11144-010-0266-z
Platinum nanoparticles, synthesized via ethanol reduction of hexachloroplatinic acid in the presence of poly-(N-vinyl-2-pyrrolidone), were anchored on magnesium aluminate spinel using a colloidal deposition method. The samples were characterized using the following methods: transmission electron microscopy, powder X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results revealed that platinum nanoparticles, with an average diameter of 2.8 nm, are homogenously dispersed on the surface of the carrier. Under very mild conditions, supported Pt/MgAl2O4 catalysts demonstrated excellent catalytic activity and high selectivity in the hydrogenation reaction of benzaldehydes to benzyl alcohols. The reaction kinetics for the catalytic hydrogenation of 3-phenoxybenzaldehyde to 3-phenoxybenzyl alcohol on a Pt/MgAl2O4 catalyst can be described by equation \( r = k \times c^{1.44} \times p_{{{\text{H}}_{ 2} }} \), and the apparent activation energy is 35.6 kJ mol−1.
Co-reporter:Congbin Fan, Ping Yang, Xiaomei Wang, Gang Liu, Xiaoxia Jiang, Hongzheng Chen, Xutang Tao, Mang Wang, Minghua Jiang
Solar Energy Materials and Solar Cells 2011 95(3) pp: 992-1000
Publication Date(Web):
DOI:10.1016/j.solmat.2010.12.010
Co-reporter:Mingshan Zhu, Ming Han, Yukou Du, Ping Yang, Xiaomei Wang
Dyes and Pigments 2010 Volume 86(Issue 1) pp:81-86
Publication Date(Web):June 2010
DOI:10.1016/j.dyepig.2009.12.004
A tetraphenylporphyrin bearing four naphthalene donor moieties (5,10,15,20-tetrakis(4-(naphthalen-1-ylmethoxy)phenyl)porphyrin were synthesized and characterized using 1H NMR, FTIR, UV–vis, FL, TEM, and XRD. Substituting the naphthalene groups onto the porphyrin ring led the molecule to absorb over a broader range (200–700 nm) and to undergo efficient intramolecular energy transfer from the naphthalene to the porphyrin ring. FTIR, XRD and TEM analyses indicated that within a functionalized platinum nanocomposite comprising the porphyrin, the photoreceptive dye forms a shell containing a nanosize Pt core (∼2.8 nm). The photocatalytic activity of the Pt nanocomposite towards water reduction to hydrogen was >twice that of a Pt-naphthalene-free porphyrin system. The turnover numbers (TONPt and TONdye) and quantum yields of hydrogen (ΦH2)(ΦH2) were 72, 7200 and 3.0%, respectively, calculated on the basis of the total amount of H2 evolved after 12 h irradiation.
Co-reporter:Manhuan Cheng;Yongtao Lu;Xiaomei Wang
Colloid Journal 2010 Volume 72( Issue 6) pp:866-873
Publication Date(Web):2010 December
DOI:10.1134/S1061933X10060190
Pt-(diphenylamino styryl benzylazanediyl) diacetic acid derivatives nanocomposites were synthesized via the alcohol reduction method and used as catalysts for hydrogenation of benzaldehydes including benzaldehyde, 3-phenoxybenzaldehyde, 4-hydroxybenzaldehyde, 4-anisaldehyde, and 4-dimethylaminobenzaldehyde. The nanocomposites characterized by UV-Vis, XRD and TEM have mean sizes of platinum cores from 1.8 to 2.9 nm. The size depends on the molar ratio of platinum and the organic compound in the nanocomposites. The Pt nanocomposites are stable not only in the colloidal solution but also during the catalytic hydrogenation process. The results of the catalytic hydrogenation of benzaldehyde derivatives demonstrate that the catalytic activity of the nanocomposites is much higher than that of Pt nanoparticles stabilized by Fréchet-type dendrimers under the same reaction conditions. High activity of the catalysts may be attributed to the relatively open dendritic shell of the nanocomposite, which provides large tunnels for the substrates moving from the surface to the active sites.
Co-reporter:Xiuli Li, Baozong Li, Manhuan Cheng, Yukou Du, Xiaomei Wang, Ping Yang
Journal of Molecular Catalysis A: Chemical 2008 Volume 284(1–2) pp:1-7
Publication Date(Web):2 April 2008
DOI:10.1016/j.molcata.2007.12.023
Pt/Pd and Pt/Au bimetallic nanoparticles stabilized by octa(diacetic aminophenyl)silsesquioxanes (OAAPS) were prepared and used as catalysts for hydrogenation of phenyl aldehydes to phenyl alcohols with dihydrogen under mild conditions. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV–vis absorption spectroscopy showed that nearly monodisperse nanoparticles having average diameters of 2.6 ± 0.5 and 3.1 ± 0.7 nm for Pt/Pd and Pt/Au bimetallic nanoparticles formed. The colloidal solution of the bimetallic nanoparticles stabilized by OAAPS is stable without precipitation for 3 months at room temperature since OAAPS can offer strong bonding to the bimetallic nanoparticles through the chelating effect. Pt/Pd bimetallic nanoparticles stabilized by OAAPS showed much higher catalytic activity for the hydrogenation of phenyl aldehydes to phenyl alcohols than their monometallic counterparts. The Pd atoms in Pt/Pd nanoparticles promoted the activity of the catalytic hydrogenation mainly through geometric and electronic effects. The bimetallic nanoparticles stabilized by OAAPS can be separated from the reaction system and reused by simply adjusting the pH of the colloidal solution.Pt/Pd and Pt/Au bimetallic nanoparticles stabilized by octa(diacetic aminophenyl)silsesquioxanes (OAAPS) were prepared and used as catalysts for hydrogenation of phenyl aldehydes to phenyl alcohols with dihydrogen under mild conditions. Pt/Pd bimetallic nanoparticles stabilized by OAAPS showed much higher catalytic activity for the hydrogenation of phenyl aldehydes to phenyl alcohols than their monometallic counterparts. The Pd atoms in Pt/Pd nanoparticles promoted the activity of the catalytic hydrogenation mainly through geometric and electronic effects.
Co-reporter:Zezhu Huang, Xiaomei Wang, Bo Li, Changgui Lv, Jun Xu, Wanli Jiang, Xutang Tao, Shixiong Qian, Yiping Chui, Ping Yang
Optical Materials 2007 Volume 29(Issue 8) pp:1084-1090
Publication Date(Web):April 2007
DOI:10.1016/j.optmat.2006.04.011
A series of new (E)-4,4′-bis(diphenylamino)stilbene derivatives have been synthesized to investigate nonlinear absorptivities with attention paid to the peripheral substituent effect and multibranched modification effect by the open aperture femtosecond Z-scan technique and the nanosecond nonlinear optical transmission (NLT), respectively. Comparing the two-photon absorptivity (TPA) observed of (E)-4,4′-bis(diphenylamino)stilbene (BDPAS) with those of its derivatives, we found that substituent group attached to the periphery of BDPAS has no obvious contribution to enhancement TPA and that the dramatic increase of effective TPA cross-sections of multibranched samples in nanosecond regime strongly suggests their larger excited-state absorption.
Co-reporter:Jingtao Dai, Yukou Du, Fangwei Wang, Ping Yang
Physica E: Low-dimensional Systems and Nanostructures 2007 Volume 39(Issue 2) pp:271-276
Publication Date(Web):September 2007
DOI:10.1016/j.physe.2007.06.034
Magnetic PtCo/Au nanocomposites with narrow size distribution were synthesized in a reverse micelle, followed by a post-synthesis handling of the stabilizer-exchange technique. The PtCo/Au nanocomposites were characterized by ultraviolet visible spectroscopy, X-ray diffraction and transmission electron microscopy, respectively. Superconducting quantum interference device studies revealed that the nanocomposites were superparamagnetic above the blocking temperature (TB=69 K), while the samples were ferromagnetic with Hc (628 Oe) and Ms (2.97 emu/g) at 5 K.
Co-reporter:Fan Yang;Chao Liu;Fengqing Gao;Mingyu Su;Xiao Wu
Biological Trace Element Research 2007 Volume 119( Issue 1) pp:77-88
Publication Date(Web):2007 October
DOI:10.1007/s12011-007-0046-4
The improvement of spinach growth is proved to relate to N2 fixation by nano-anatase TiO2 in this study. The results show that all spinach leaves kept green by nano-anatase TiO2 treatment and all old leaves of control turned yellow white under culture with N-deficient solution. And the fresh weight, dry weight, and contents of total nitrogen, \( {\text{NH}}^{ + }_{4} \), chlorophyll, and protein of spinach by nano-anatase TiO2 treatment presented obvious enhancement compared with control. Whereas the improvements of yield of spinach were not as good as nano-anatase TiO2 treatment under N-deficient condition, confirming that nano-anatase TiO2 on exposure to sunlight could chemisorb N2 directly or reduce N2 to NH3 in the spinach leaves, transforming into organic nitrogen and improving the growth of spinach. Bulk TiO2 effect, however, was not as significant as nano-anatase TiO2. A possible metabolism of the function of nano-anatase TiO2 reducing N2 to NH3 was discussed.
Co-reporter:Ming Shen, Yukou Du, Nanping Hua, Ping Yang
Powder Technology 2006 Volume 162(Issue 1) pp:64-72
Publication Date(Web):16 February 2006
DOI:10.1016/j.powtec.2005.09.007
The hydrophobic gold nanoparticles protected with octadecylamine, tetradecylamine and decylamine, respectively, were prepared by using ethanol reduction in reverse micelle through microwave dielectric heating. In this experiment, the commonly used toxic and highly volatile organic solvents such as chloroform, toluene and so on, which were an obstacle for preparing hydrophobic nanoparticles under microwave irradiation, were replaced by a safe organic mixed solvent n-heptane/ethanol used as an oil phase. The various alkylamine-stabilized gold nanoparticles obtained through this method were characterized and analyzed by ultraviolet visible spectroscopy (UV–vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and elemental analysis. When the molar ratio of alkylamine to HAuCl4 was 40 : 1, the average diameters and standard deviations for octadecylamine-, tetradecylamine- and decylamine-capped gold nanoparticles were 4.53 ± 0.79, 5.22 ± 1.66, and 4.09 ± 1.22 nm, respectively. Furthermore, the composition of octadecylamine-stabilized gold nanoparticles was determined to be (C18H37NH2)265·Au2822, and the experimental result showed that both the monodispersity and stability of these gold nanoparticles were beneficial to forming large areas of ordered two-dimensional arrangement at the air/water interface.
Co-reporter:Ming Shen, Zunyi Wu, Hui Huang, Yukou Du, Zhigang Zou, Ping Yang
Materials Letters 2006 Volume 60(Issue 5) pp:693-697
Publication Date(Web):March 2006
DOI:10.1016/j.matlet.2005.09.068
Carbon-doped anatase TiO2 (C-TiO2) was prepared by mild oxidation of titanium carbide (TiC). The transformation of TiC to anatase TiO2 was complete when TiC was calcined in air at 350 °C for 8 h. The as-prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV−visible spectroscopy and BET adsorption measurement. The absorption spectrum of the C-TiO2 showed a stronger absorption in the UV–visible range and about 36 nm red shift of the spectrum onset compared with one of anatase TiO2 nanoparticles. The change of the spectra is attributed to ca. 0.7 wt.% carbon substitutions at oxygen sites in the sample. Compared with nanocrystalline anatase TiO2, the C-doped TiO2 powders exhibited photoactivity to trichloroacetic acid (TCA) degradation under visible light irradiation. The effects of iron doping on the sample and the pH of the solution on the photodegradation of TCA were also investigated.
Co-reporter:Ming Shen, Yukou Du, Ping Yang, Long Jiang
Journal of Physics and Chemistry of Solids 2005 Volume 66(Issue 10) pp:1628-1634
Publication Date(Web):October 2005
DOI:10.1016/j.jpcs.2005.05.078
The hydrophobic gold nanostructures with different shapes were prepared by using n-butanol situ reduction in cetyltrimethylammonium bromide (CTAB)/n-butanol/n-heptane/HAuCl4(aq) W/O microemulsion through microwave dielectric heating. The CTAB-stabilized gold nanoparticles and nanowires with a networked structure obtained through this method were characterized and analyzed by ultraviolet visible spectroscopy (UV–vis), transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. The morphologies of the hydrophobic gold nanocrystals were successfully controlled through the adjustment of molar ratios of CTAB/HAuCl4 in the reverse microemulsion. The formation mechanism of anisotropic gold nanostructures was discussed, which demonstrated that CTAB played an important role in forming and stabilizing the shape of gold nanowires.
Co-reporter:Ping Yang, Cheng Lu, Nanping Hua, Yukou Du
Materials Letters 2002 Volume 57(Issue 4) pp:794-801
Publication Date(Web):December 2002
DOI:10.1016/S0167-577X(02)00875-3
Nanoparticles of titanium dioxide co-doped with Fe3+ and Eu3+ were prepared using the sol–gel method. The photocatalytic reactivities were evaluated by photodegradation of chloroform in solution. Nanocrystalline TiO2 co-doped with Eu3+ and Fe3+ at optimal concentration (1 at.% Fe3+, 0.5 at.% Eu3+) shows a synergistic effect, which significantly increases the photodegradation activity of nano-TiO2. The effects of the dopants in nanocrystalline TiO2 particles on the photocatalysis were studied using the photo-electrochemical method. Two dopants of Fe3+ and Eu3+ in nanocrystalline TiO2 play different roles in improving the photoinduced charge separation in the nanostructured semiconductor and in the interfacial charge transfer process at the semiconductor/solution interface. Fe3+ serves as a hole trap and Eu3+ as an electron trap in nanocrystalline TiO2, respectively. The separation of the charge carriers is attributed to such trappings. In the meantime, Fe3+ and Eu3+ also speed up anodic and cathodic processes via improving interfacial charge transfers. Superior photocatalysis of nanocrystalline TiO2 co-doped with Fe3+ and Eu3+ ions was related to the cooperative actions of the two dopants.
Co-reporter:Yuejun Song, Lianyan Wang, Ping Yang, Robert M. Wenslow, ... Zongwu Deng
Journal of Pharmaceutical Sciences (June 2013) Volume 102(Issue 6) pp:1915-1923
Publication Date(Web):1 June 2013
DOI:10.1002/jps.23538
To improve the dissolution and hence the oral bioavailability, amorphous felodipine (FEL) solid dispersions (SDs) with Kollidon® VA 64 (PVP/VA) were prepared. Hot-melt extrusion was employed with an extruding temperature below the melting point (Tm) of FEL. X-ray powder diffraction (XRPD) and 13C CP/MAS nuclear magnetic resonance (NMR) measurements show that the extrudates are amorphous. The intermolecular interaction between FEL and PVP/VA in SDs was investigated by Fourier transform infrared spectroscopy, 15N CP/MAS NMR, and 1H high-resolution MAS NMR. Furthermore, a single glass transition temperature (Tg) was detected by differential scanning calorimetry in addition to a single 1H T1 or T1rho relaxation time detected by 13C NMR signals. These results confirm that the extru-dates contain FEL dispersed into the polymer matrix at a molecular level with no detectable phase separation. This molecular-scale mixing results in a significantly faster dissolution rate compared with the pure crystalline FEL. Additionally, the molecular-scale mixing prevents the amorphous drug from recrystallizing even after being stored at 40°C/75% Relative Humidity for 2 months.
Co-reporter:Yijie Wu, Dongmei Chu, Ping Yang, Yukou Du and Cheng Lu
Catalysis Science & Technology (2011-Present) 2015 - vol. 5(Issue 6) pp:NaN3382-3382
Publication Date(Web):2015/04/24
DOI:10.1039/C5CY00439J
A novel ternary nanocomposite comprising mesoporous WO3, Mn3O4 nanoparticles and N-doped graphene was prepared by a one-pot deposition method. The nanocomposite was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The results demonstrated that the Mn3O4 nanoparticles had been successfully hybridized with the mesoporous WO3 and the WO3/Mn3O4 hybrid was well dispersed on the surface of N-doped graphene with superior interactions. The nanocomposite exhibits higher photocatalytic activity for water oxidation than the individual mesoporous WO3 and WO3/Mn3O4 catalysts. The amount of oxygen evolution from the optimized heterostructural photocatalyst (1.5 wt% Mn3O4 and 2 wt% N-doped graphene) was 294 μmol g−1, which was about 3.6 times as high as that from m-WO3. The heterostructure formed between Mn3O4 and m-WO3 enhances photogenerated electron/hole transfer and restrains the recombination of charges greatly. N-doped graphene in the nanocomposite acting as an excellent electron acceptor and mediator also contributes to the increase in photocatalytic performance by promoting the separation and transfer of photogenerated charges. This study suggests a promising method to enhance photocatalytic activity by combining the heterostructural WO3/Mn3O4 hybrid with graphene in a ternary system.
Co-reporter:Zhigang Mou, Shunli Yin, Mingshan Zhu, Yukou Du, Xiaomei Wang, Ping Yang, Junwei Zheng and Cheng Lu
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 8) pp:NaN2799-2799
Publication Date(Web):2012/12/14
DOI:10.1039/C2CP44270A
A novel composite composed of TiSi2, graphene and RuO2 nanoparticles was fabricated by a one-pot deposition method using reduced graphene oxide (RGO) as a supporting matrix and RuCl3 as the RuO2 precursor. The resulting RuO2/TiSi2/RGO composite was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectra, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectra, photoelectrical response and electrochemical impedance spectra. The results indicated that the three components in the composite were effectively contacted, thus facilitating the photogenerated charges transfer and separation through multiple routes. By using the composite as a photocatalyst for visible-light water splitting the average hydrogen production rate could reach 97.5 μmol h−1 g−1, which is higher than that from RuO2/TiSi2 and pure TiSi2 systems under the same conditions.
Co-reporter:Shunli Yin, Xiaomei Wang, Zhigang Mou, Yijie Wu, Hui Huang, Mingshan Zhu, Yukou Du and Ping Yang
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 23) pp:NaN11296-11296
Publication Date(Web):2014/03/11
DOI:10.1039/C4CP00384E
A novel nanocomposite consisting of α-Fe2O3, Mn3O4 and reduced graphene oxide (r-GO) has been facilely synthesized through a two-step method: solvothermal reaction for Mn3O4-modified α-Fe2O3 (α-Fe2O3/Mn3O4) and self-assembly process for combining α-Fe2O3/Mn3O4 with r-GO (α-Fe2O3/Mn3O4/r-GO). The morphology and structure of the nanocomposite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that rod-like hematite was modified by Mn3O4 and dispersed on the surface of r-GO. Raman and Fourier transform infrared spectra (FTIR) showed superior interfacial contacts between α-Fe2O3/Mn3O4 and r-GO. Ultraviolet-visible diffuse reflectance spectroscopy (DRS) and photoelectrochemical characterization revealed a high light-harvesting efficiency, a lowered overpotential for water oxidation and an excellent charge transfer performance of α-Fe2O3/Mn3O4/r-GO nanocomposite with heterostructures. The photocatalytic oxygen evolution from the optimized photocatalyst was up to 1406.2 μmol g−1 in 10 h of UV-vis light irradiation and the quantum yield was ca. 4.35% at 365 nm. Our investigation suggests that constructing a catalyst with heterostructures is a promising method to enhance photocatalytic activity.
Co-reporter:Mingshan Zhu, Yupei Dong, Bin Xiao, Yukou Du, Ping Yang and Xiaomei Wang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 45) pp:NaN23779-23779
Publication Date(Web):2012/09/20
DOI:10.1039/C2JM35322A
Herein, we report an efficient photocatalytic hydrogen evolution system based on Ru-tris(dicarboxybipyridine)–reduced graphene oxide (Ru(dcbpy)3–RGO) hybrid. AFM images and UV-vis spectra validate Ru(dcbpy)3 functionalized RGO via noncovalent interactions. Fluorescence and Raman spectra suggest that Ru(dcbpy)3 acts as an electron donor and RGO serves as an electron acceptor in the hybridized species. Moreover, the photocurrent experiment further confirms that the photoelectrons transfer from Ru(dcbpy)3 to RGO nanosheets and then flow to deposited Pt nanoparticles effectively. Compared with the corresponding single-component Ru(dcbpy)3 and RGO nanosheets, the Ru(dcbpy)3–RGO hybrid displays distinctly enhanced photocatalytic activities under UV-vis or visible light irradiation. Therein, RGO acts as a solid-state electron mediator, which facilitates charge separation and suppresses recombination of photoexcited electron–hole pairs in RGO–Ru(dcbpy)3. Furthermore, the effect of reaction parameters such as pH, the composition of the hybrid and the stability of catalytic performance are also investigated. This study might initiate new possibilities for the development of novel graphene-based photocatalysts with enhanced activity via facile noncovalent modification of graphene with organic photosensitizers.
Co-reporter:Zhangquan Yao, Mingshan Zhu, Fengxing Jiang, Yukou Du, Chuanyi Wang and Ping Yang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 27) pp:NaN13713-13713
Publication Date(Web):2012/05/10
DOI:10.1039/C2JM31683H
In this paper, a facile electrochemical approach is developed towards synthesizing Pt nanoflowers modified reduced graphene oxide (RGO) wrapped carbon cloth (CC) as an anode (Pt nanoflowers/RGO/CCE) for formic acid and methanol electrooxidation. As revealed by SEM measurements, the carbon cloth is well wrapped by the RGO, and the RGO wrapped carbon cloth serves as an excellent support for electrochemically anchoring Pt nanoflowers, being more well-dispersed than without RGO. Compared with Pt nanoparticles/CCE, Pt nanoparticles/RGO/CCE, and Pt nanoflowers/CCE, the Pt nanoflowers/RGO/CCE displays a distinctly enhanced current density of CVs towards formic acid and methanol electrooxidation. The utilization of graphene results in well-dispersed Pt nanostructures with a uniform size and unique morphology structure; a relatively large surface area; and excellent electron or charge transfer rate, contributing to the enhanced electrocatalytic activity. The work likely opens up new promise for developing novel, low-cost yet highly efficient carbon material-based electrodes, especially for direct formic acid fuel cells and direct methanol fuel cells.
Co-reporter:Hui Huang, Zongkuan Yue, Gang Li, Xiaomei Wang, Jie Huang, Yukou Du and Ping Yang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 47) pp:NaN20125-20125
Publication Date(Web):2014/10/06
DOI:10.1039/C4TA04106B
A novel composite of In2O3 nanorods (INR) hybridized with reduced graphene oxide (RGO) was fabricated by a facile UV-assisted photoreduction method. The as-prepared samples were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The one-dimensional INR with high surface-to-volume ratio anchored on the surface of RGO homogeneously, resulting in a nice interfacial contact between INR and RGO. The photocatalytic activities of the INR–RGO composites were investigated for 4-chlorophenol (4-CP) degradation under UV-vis or visible light irradiation. The photodegradation yield of the optimized photocatalyst reached 91.6%, which was about 1.9 times as high as that of INR under visible light irradiation (>400 nm). The enhanced photocatalytic activity of the INR–RGO composites can be ascribed to the efficient interfacial charge transfer from INR to RGO, which resulted in the prolonged lifetime of the photoinduced charge carriers.
Co-reporter:Dandan Wang, Jie Huang, Xia Li, Ping Yang, Yukou Du, Cynthia M. Goh and Cheng Lu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 8) pp:NaN4202-4202
Publication Date(Web):2014/12/16
DOI:10.1039/C4TA05721J
In this paper, a manganese phthalocyanine (MnPc) covalently functionalized graphene nanohybrid (MnPcG) has been successfully synthesized via 1,3-dipolar cycloaddition, and used as a photocatalyst after modifying it with platinum nanoparticles via photodeposition. The nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis, Fourier transform infrared (FTIR), and Raman spectroscopy. These characterization results confirmed the grafting of MnPc moiety onto the graphene sheets. The intermolecular electron transfer was facilitated and the photoexcited charges recombination was suppressed as confirmed by the fluorescence quenching and enhanced photocurrent density in MnPcG nanohybrid. In comparison to graphene, the MnPcG nanohybrid shows a substantial improvement in the photocatalytic hydrogen evolution. The yields of hydrogen production of MnPcG/Pt reached to 8.59 and 1.45 μmol mg−1 under 10 h of UV-vis and visible light (λ > 400 nm) irradiation, respectively. This work demonstrates that metallophthalocyanines covalently functionalized graphene is a novel photocatalyst for solar energy conversion to produce hydrogen from water.
Co-reporter:Mingshan Zhu, Yukou Du, Ping Yang and Xiaomei Wang
Catalysis Science & Technology (2011-Present) 2013 - vol. 3(Issue 9) pp:NaN2302-2302
Publication Date(Web):2013/05/21
DOI:10.1039/C3CY00236E
In this paper, a novel porphyrin dye (5,10,15,20-tetrakis (4-(anthracene-1-ylmethoxy)phenyl) porphyrin, TPPAN) and its functionalized platinum nanoparticles (Pt-TPPAN) were synthesized. Using the Pt-TPPAN nanocomposite as a photocatalyst, a new and more compact photoinduced hydrogen evolution system from an aqueous ethanol solution without additives was developed. Fluorescence and photo-electrochemical spectra reveal that photoinduced electron transfer occurs from the photoexcited state of anthracene substituents to the porphyrin, accompanied by an electron transfer from the excited porphyrin moiety to the Pt co-catalyst. The photocatalytic activity results suggested that this TPPAN functionalized Pt nano-assembly could efficiently catalyze hydrogen evolution from an aqueous ethanol solution under simulated solar light irradiation. Therein, the TPPAN molecule in the nanocomposite worked as a light absorption antenna and the nanocore Pt species acted as a co-catalyst. This investigation might offer a new paradigm for constructing a simpler and more efficient homogeneous photocatalytic hydrogen evolution system for mimicking natural photosynthesis.
Co-reporter:Yongtao Lu, Dandan Wang, Ping Yang, Yukou Du and Cheng Lu
Catalysis Science & Technology (2011-Present) 2014 - vol. 4(Issue 8) pp:NaN2657-2657
Publication Date(Web):2014/04/17
DOI:10.1039/C4CY00331D
A novel nanocomposite composed of two-dimensional graphene-like MoS2 and ZnxCd1−xS (0 ≤ x ≤ 0.5) nanoparticles has been synthesized by a simple exfoliation of bulk MoS2 into single- or few-layer MoS2 and then ultrasonic mixing of ZnxCd1−xS onto MoS2 nanosheets. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), photoelectrochemical experiments and photoluminescence spectroscopy. The results show that the nanoparticles of ZnxCd1−xS are well dispersed and anchored on the surface of the graphene-like MoS2 nanosheets. The superior interfacial coupling between ZnxCd1−xS and MoS2 synergistically promoted the electron–hole transportation and separation. Upon visible-light irradiation (λ > 420 nm), the composite consisted of Zn0.3Cd0.7S and ca. 0.6 wt% graphene-like MoS2 gave the highest hydrogen evolution amount of 7179.1 μmol g−1, which is ca. 7 times as high as that of Zn0.3Cd0.7S. This study shows a facile method to build a low-cost but effective photocatalyst for water reduction to produce hydrogen under solar light irradiation.
Co-reporter:Yongtao Lu, Dongmei Chu, Mingshan Zhu, Yukou Du and Ping Yang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 26) pp:NaN17361-17361
Publication Date(Web):2015/05/27
DOI:10.1039/C5CP01657F
A binary composite composed of two dimensional (2D) ultrathin carbon nitride (C3N4) nanosheets and NiS nanoparticles was synthesized and applied as a noble-metal-free photocatalyst for hydrogen evolution under visible light irradiation. The ultrathin nanosheets of C3N4 were obtained by a facile liquid exfoliation method and used as 2D supports for the deposition of NiS nanoparticles. In the binary composite, the ultrathin C3N4 nanosheets acted as a visible light responding semiconductor, and the NiS nanoparticles served as a noble-metal-free cocatalyst. The binary composite with an optimized composition gave a hydrogen evolution rate comparable to that of Pt modified C3N4. Moreover, compared to bulk C3N4, the exfoliated C3N4 nanosheets distinctly improve the photocatalytic performance for hydrogen evolution. The photocatalytic results combined with photoelectrochemical experiments show that C3N4 with an ultrathin structure promotes the electron–hole separation and transportation during the process of the photoinduced hydrogen evolution. This study displays a facile method to build a low-cost but effective photocatalyst for hydrogen production under visible light irradiation.
Co-reporter:Hui Huang, Zongkuan Yue, Gang Li, Xiaomei Wang, Jie Huang, Yukou Du and Ping Yang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 47) pp:NaN15116-15116
Publication Date(Web):2013/10/11
DOI:10.1039/C3TA13433D
In this paper, we report the synthesis, characterization, and photocatalysis of a novel composite, composed of high-ordered mesoporous WO3 (m-WO3) and reduced graphene oxide (RGO). The composite was systematically characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, N2 adsorption–desorption and UV-visible diffuse reflectance spectroscopy techniques. The superior contact between two moieties in the composites facilitates the charge carrier separation and the evolution of oxygen. Under visible light irradiation, the amount of oxygen evolution from the optimized photocatalyst containing ca. 6 wt% RGO reached 437.3 μmol g−1, which was 5.1 times as high as that from m-WO3. The enhancement of photocatalytic activity could be ascribed to the fact that RGO acts herein as a solid-state electron mediator, promoting the charge transportation and separation, as well as suppressing the electron–hole recombination in the composite. This study might provide a prototype for constructing a novel photocatalytic system by hybridizing graphene with a mesoporous semiconductor for solar energy conversion.
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