_{Preparation Doping Effect And Heterojunction SnWO 4} Catalytic Properties Of Nanomaterials Based On Its Visible Light

Photocatalysis technology is one of main efficient ways to solve the problems ofglobal increasingly serious environment pollutions and energy crisis. Developinghigh-performance pholocatalyst with high quantum efficiency and can take full advantageof solar energy is key point. Stannous tungstate (SnWO4) has received considerableattention due to its many advantages such as strong visble light response (band gap isabout1.7eV) and abound resources. On the other hand, α-SnWO4suffers from the slowmigration rate and quick recombination between electrons and holes, which will notablydegrade its photocatalytical activity. In this work, ion-doping and hybiding techniqueswere employed to improve the photocatalytical properties of α-SnWO4and the researchcontents are as follows.1. α-SnWO4nanocrystals were prepared using simple solvothermal method. Theas-prepared samples were sheet-like with smooth surface and their sizes were about50-100nm. Conditions affecting the microstructure and photocatalytical properties of α-SnWO4nanosheets were investigated and results showed that the sample prepared at pH of7.0exhibits the highest photocatalytical activity.2. α-SnWO4/SnO2heterostructure were synthesized using two-step hydrothermalprocess. The as-synthesized products were sheet-like with sizes about50-100nm, which isconsistent with that of the pure α-SnWO4. Contrary to the smooth surface of pureα-SnWO4nanosheet, the surface of α-SnWO4/SnO2heterostructure was very roughness,which is ascribed to the accumulation of SnO2nanoparticles onto the surface ofα-SnWO4nanosheet. Such a microstructure resulted in larger surface area of α-SnWO4/SnO2heterostructure than that of pure α-SnWO4. Furthermore, there existed an effectiveheterojunction interface between SnO2nanoparticles and α-SnWO4nanosheets, which wasconfirmed by FTIR spectra. Photocatalytic activities of the samples were evaluated by thephotocatalytic degradation of MO under visible light. The experimental results suggestedthat the α-SnWO4/SnO2heterostructure possesses excellent photocatalytic properties withgood recyclability. The enhanced photocatalytic performance was attributed to the effectiveseparation of photogenerated electron-hole pairs at the α-SnWO4/SnO2heterojunctioninterface. 3. Bi3+-doped α-SnWO4nanosheets at different concentrations were systematicallystudied. It was found that the Bi3+-doping concentration has great effect on themicrostructure and photocatalytic properties of α-SnWO4nanocrystals. As a result, thehighest photocatalytic activities was achieved for the sample of α-SnWO4:0.005Bi (mol%)and the corresponding mechanism was discussed.