Tian Lv

Microwave-assisted synthesis of ZnO–graphene composite for photocatalytic reduction of Cr(VI)

ZnO–graphene composites are successfully synthesized via microwave-assisted reaction of zinc sulfate in aqueous solution with a graphite oxide dispersion using a microwave synthesis system. Their morphology, structure and photocatalytic performance in reduction of Cr(VI) are characterized by scanning electron microscopy, X-ray diffraction spectroscopy and UV-vis absorption spectrophotometer, respectively. The results show that in the composite the graphene nanosheets are decorated densely by ZnO nanosheets, which display a good combination between graphene and ZnO nanosheets. The ZnO–graphene composite exhibits an enhanced photocatalytic performance in the reduction of Cr(VI) with a removal rate of 98% under UV light irradiation as compared with pure ZnO (58%) due to the increased light absorption intensity and range, as well as the reduction of electron–hole pair recombination with the introduction of graphene.

Microwave-assisted synthesis of TiO2-reduced graphene oxide composites for the photocatalytic reduction of Cr(VI)

TiO2-reduced graphene oxide (RGO) composites are successfully synthesized via the microwave-assisted reduction of graphite oxide in a TiO2 suspension using a microwave synthesis system. Their morphology, structure and photocatalytic performance in the reduction of Cr(VI) are characterized by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction spectroscopy and UV-vis absorption spectrophotometer. The results show that in the composite the RGO nanosheets are densely decorated by TiO2 nanoparticles, which displays a good combination between RGO and TiO2. TiO2–RGO composites exhibit enhanced photocatalytic performance for the reduction of Cr(VI) with a maximum removal rate of 91% under UV light irradiation as compared with pure TiO2 (83%) and commercial TiO2 P25 (70%) due to the increased light absorption intensity and range as well as the reduction of electron-hole pair recombination in TiO2 with the introduction of RGO.

Enhanced photocatalytic degradation of methylene blue by ZnO–reduced graphene oxide–carbon nanotube composites synthesized via microwave-assisted reaction

ZnO–reduced graphene oxide (RGO)–carbon nanotube (CNT) composites were successfully synthesized via microwave-assisted reduction of a graphite oxide dispersion in zinc nitrate solution with a CNT suspension. Their photocatalytic performance in the degradation of methylene blue was investigated and the results show that the CNTs play an important role in the enhancement of the photocatalytic performance and the ZnO–RGO–CNT composite with 3.9 wt% CNTs achieves a maximum degradation efficiency of 96% under UV light irradiation for 260 min as compared with ZnO–RGO (88%) due to the increased light absorption and the reduced charge recombination with the introduction of CNTs.

One-step synthesis of CdS–TiO2–chemically reduced graphene oxide composites via microwave-assisted reaction for visible-light photocatalytic degradation of methyl orange

One-step synthesis of CdS–TiO2–chemically reduced graphene oxide (RGO) composites was carried out using microwave-assisted reduction of graphite oxide in CdS precursor solution with TiO2 suspension. The photocatalytic performance of CdS–TiO2–RGO composites in degradation of methyl orange was examined. Results show that the RGO addition could enhance the photocatalytic performance of CdS–TiO2 composites with maximum degradation efficiency of 99.5% under visible light irradiation as compared with the pure TiO2 (43%) and CdS–TiO2 (79.9%) composites due to the increase of specific surface area for more adsorbed MO and the reduction of electron–hole pair recombination with the introduction of RGO.

Zn-doped nanocrystalline TiO2 films for CdS quantum dot sensitized solar cells

Quantum dot-sensitized solar cells based on Zn-doped TiO(2) (Zn-TiO(2)) film photoanode and polysulfide electrolyte were fabricated. Zn-TiO(2) nanoparticles were obtained via a hydrothermal method and screen printed on the fluorine-doped tin oxide glass to prepare the photoanode. The structure, morphology and impedance of the Zn-TiO(2)/CdS film and the photovoltaic performance of the Zn-TiO(2)/CdS cell were investigated. It was found that the photovoltaic efficiency was improved by 24% when the Zn-TiO(2) film was adopted as the photoanode of CdS QDSSCs instead of only the TiO(2) layer. The improvement was ascribed to the reduction of electron recombination and the enhancement of electron transport in the TiO(2) film by Zn doping.

Visible light photocatalytic degradation of dyes by bismuth oxide-reduced graphene oxide composites prepared via microwave-assisted method

Bi2O3-reduced graphene oxide (RGO) composites were successfully synthesized via microwave-assisted reduction of graphite oxide in Bi2O3 precursor solution using a microwave system. Their morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) and methyl orange (MO) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, UV-vis absorption spectroscopy, and electrochemical impedance spectroscopy, respectively. The results show that the RGO addition can enhance the photocatalytic performance of Bi2O3-RGO composites. Bi2O3-RGO composite with 2 wt.% RGO achieves maximum MO and MB degradation rates of 93% and 96% at 240min under visible light irradiation, respectively, much higher than those for the pure Bi2O3 (78% and 76%). The enhanced photocatalytic performance is ascribed to the increased light adsorption and the reduction in electron-hole pair recombination in Bi2O3 with the introduction of RGO.

Au Nanoparticles as Interfacial Layer for CdS Quantum Dot-sensitized Solar Cells

Quantum dot-sensitized solar cells based on fluorine-doped tin oxide (FTO)/Au/TiO2/CdS photoanode and polysulfide electrolyte are fabricated. Au nanoparticles (NPs) as interfacial layer between FTO and TiO2 layer are dip-coated on FTO surface. The structure, morphology and impedance of the photoanodes and the photovoltaic performance of the cells are investigated. A power conversion efficiency of 1.62% has been obtained for FTO/Au/TiO2/CdS cell, which is about 88% higher than that for FTO/TiO2/CdS cell (0.86%). The easier transport of excited electron and the suppression of charge recombination in the photoanode due to the introduction of Au NP layer should be responsible for the performance enhancement of the cell.

Controlled Synthesis of Nanosized Palladium icosahedra and Their Catalytic Activity towards Formic‐Acid Oxidation

Pd icosahedra with sizes controlled in the range of 5-35 nm were synthesized in high purity through a combination of polyol reduction and seed-mediated growth. The Pd icosahedra were obtained with purity >94 % and uniform sizes controlled in the range of 5-17 nm by using ethylene glycol as both the reductant and solvent. The studies indicate that the formation of Pd nanocrystals with an icosahedral shape was very sensitive to the reaction kinetics. The success of this synthesis relies on the use of HCl to manipulate the reaction kinetics and thus control the twin structure and shape of the resultant nanocrystals. The size of the Pd icosahedra could be further increased up to 35 nm by seed-mediated growth, with 17 nm Pd icosahedra serving as seeds. The multiply twinned Pd icosahedra could grow into larger sizes, and their shape and multiply twinned structure were preserved. Thanks to the presence of twin defects, the Pd icosahedra showed a catalytic current density towards formic-acid oxidation that was 1.9 and 11.6 times higher than that of single-crystal Pd octahedra, which were also fully covered by {111} facets, and commercial Pd/C, respectively.

Electrophoretic Deposition of a Reduced Graphene–Au Nanoparticle Composite Film as Counter Electrode for CdS Quantum Dot‐Sensitized Solar Cells

A reduced graphene (RG)-Au nanoparticle composite film is successfully fabricated by electrophoretic deposition and used as counter electrode for quantum dot-sensitized solar cells. The RG-Au composite is prepared by one-step microwave-assisted reduction of chloroaurate in alkaline solution with graphite oxide dispersion. Under one sun illumination (AM 1.5 G, 100 mW cm(-2)), the cell with a RG-Au counter electrode shows an energy conversion efficiency of 1.36 %, which is higher than those of cells employing conventional Pt or Au counter electrodes, due to the superior combination of highly catalytic Au nanoparticles and the conductive graphene network structure.

Enhanced visible-light photocatalytic degradation of methyl orange by BiPO4–CdS composites synthesized using a microwave-assisted method

BiPO4–CdS composites consisting of BiPO4 nanorods and CdS nanoparticles were successfully synthesized via a microwave-assisted reaction. The photocatalytic performance of the BiPO4–CdS composites, with different proportions of CdS, in the degradation of methyl orange under visible light irradiation was investigated. The results show that the BiPO4–CdS composite with 30.1 wt% CdS achieves a better performance with a maximum degradation rate of 98.1% as compared with pure BiPO4 due to the increase of specific surface area for more adsorbed MO, the enhancement of light absorption and the reduction of carrier recombination.