Research On Synthesis, Dope, Characterization And Visible- Light Photocatalytic Properties Of Bi₂MoO₆

Photocatalysis is an emerging water treatment technology with many advantages such as simple process, efficient and energy-saving, low cost and no secondary pollution.In this paper, y-Bi2MoO6 with visible-light activity was synthesized by solid-state reaction and hydrothermal route and prepared Bi2MoO6 composite catalyst doped with Y,Sm and Yb for the first time. Morphology and structure of the Bi2Mo06 composite catalyst were characterized by XRD and other methods, and the results show that:samples synthesized by two methods were both crystallized with a orthorhombic crystal system, a space group Pca21 (29). The samples prepared by hydrothermal method was more pure and had better degree of crystallinity; Bi2MoO6 synthesized by hydrothermal method and doped with 2at% Y、Sm and Yb showed visible light response and had band gap energy of 2.53 eV、2.53 eV、2.55 eV and 2.55 eV respectively. The sample were successful doped with Y, Sm and Yb and doping ratio agreed with the stoichiometric ratio as designed; the sample prepared by hydrothermal route had fewer defects than solid-state sintering method, the doped sample had fewer defects than the undoped sample.The photocatalytic activities of Bi2MoO6 were evaluated by the degradation of Rhodamine B (RhB) and Nuclear Fast Red (NFR). Effect of catalyst loading, visible light intensity, pH of the dye solution, Inorganic salts and H2O2 on photocatalytic activity was studied. The influences of different preparation methods, different hydrothermal conditions and different doping elements were also considered, the structural stability and stability of catalytic properties were studied through the catalyst recycling experiments. The results showed that photocatalytic activity of Bi2MoO6 was proportional to photocatalyst dosage, visible light intensity and hydrogen peroxide content; the optimum dosage of Bi2MoO6 was 4 g/L, optimum pH value of the dye solution was 7, the best content of H2O2 was 0.2 mol/L; NaCl promoted the visible light photocatalytic activity of Bi2MoO6 while Na2CO3 and Na2SO4 act as a disincentive factor. The photocatalytic activity of the sample prepared by hydrothermal method was superior to the solid-phase sintering method. The best hydrothermal conditions was heated to 180 ℃ and maintained for 24 h while pH= 7. The sample doped with Y showed the best photocatalytic activity and the optimum doping amount of Y, Sm and Yb were 2%,2% and 1% respectively. Removal rate of RhB after 1 h adsorption and 5 h illumination with 2.0mol% Y-Bi2MoO6 as catalyst was 56.6%, higher than 47.6% while with nitrogen-doped titanium dioxide as catalyst. Bi2MoO6 catalyst synthesized by hydrothermal method reused four times, and removal rate of RhB through photocatalytic degradation were 32.8%,31.7%,31.1% and 27.9% respectively, and removal rate of RhB through photocatalytic degradation were 89.8%,87.6%,87.1% and 84.3% respectively, and the results showed Bi2Mo06 could be recycled and reused since it had stable structure and catalytic properties.