| Over the past years, a serious contemplation has revealed the need to resolve two major complications:global warming due to rising levels of atmospheric carbon dioxide(CO2) and the alarming consumption of energy resources. Searching for a effective means to solve the current problem is urgent. Solar fuel production from green CO2 gas would be a convenient solution to resolve both problems simultaneously. Through the solar energy, convert CO2 into hydrocarbons production from a photocatalytic way would be a convenient solution to resolve both problems simultaneously. Thus, the development of highly efficient, practical, cut-price,photocatalytic reduction of CO2 over semiconductor became one of the most hot project in modern times. After half a century of research, many significant progresses have been made in the exploitation of semiconductor, improvement of reaction system and optimization of reaction conditions, but the the current photocatalytic reduction of CO2 technology still faces low conversion efficiency and it is difficult to control the selectivity of products. In our study, we mainly investigations Bi2WO6 materials and modified Bi2WO6 materials applied in preparation of methanol from photocatalytic reduction of CO2.(1) Platelet-Bi2WO6 and Button-Bi2WO6 material were prepared through a hydrothermal process by using lysine(Lys) and polyvinylpyrrolidone(PVP) as a surfactant reagent at 160 oC, we get a Hollow-Bi2WO6 powers through a ion-exchange method by using BiOBr as precursor. The obtained Bi2WO6 material were used as photocatalyst for the reduction of CO2 in the suspension system, and exhibited a selective methanol and ethanol production under visible-light irradiation. The Hollow-Bi2WO6 have larger specific surface area, as far as we know the photocatalytic efficiency and product selectivity affected by the microstructure of materials. Finally, the pathway for reduction of CO2 have been proposed.(2) In order to promoted the photocatalytic activity, the conductive polymers we composited in the material surface of Hollow-Bi2WO6 by in situ copolymerizationmethod. The experimental results indicated that the introduction of conducting polymer obviously enhanced visible light absorption ability and the migration efficiency of photogenerated charge carries, and decreased the recombination of photogenerated electron-hole pairs. According to XRD, SEM, EDS and Raman analysis, a series of conducting polymers(PPy, PANI, and PTh) modified Bi2WO6 hierarchical hollow microsphere(HHMS) were successfully synthesized. It was found that the methanol and ethanol yield of PTh/Bi2WO6 was 56.5 and 20.5 μmol/gcat,respectively, which is 2.8 times higher than that of pure Bi2WO6.(3) The solid solution Bi2WxMo1-xO6 materials synthesized by coprecipitation method, because of a similar crystal structure between Bi2WO6 and Bi2MoO6, and a similar ionic radius between W6+ and Mo6+. We have study the affection on band gap with different amount of Mo atoms doping. The results show that Mo6+ gradually replace W6+ in the crystal lattice with the increase of the Mo doping, then, leading to restructuring of electronic structure. It has been reported that the CB of Bi2WO6 is composed of W 5d orbitals and the VB is composed of Bi 6s and O 2p hybrid orbitals.The hybridization of Mo 4d and W 5d orbitals makes the CB elevation, and the hybridization of Bi 6s and O 2p makes the VB largely dispersed. We get solid solution materials with the narrow band gap at optimal ratios between W and Mo was 1:3,which showed the strongest response and highest catalytic efficiency under visible light. |
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