Theoretical Study Of Metal And Non-metal Doped Bi₁₂TiO₂₀ And Its Photocatalytic Performance

Photocatalytic technology has been paid much attention,as a new green technology to solve the problems of energy and environment.As the earliest photocatalyst,TiO2 was widely studied because of the good performance.But the scope of visible light absorption spectrum was limit by the structure of the TiO₂photocatalyst.Although TiO₂ has been researched for using in the past few years,there are still defects.Therefore,it is important to develop new photocatalyst materials.In a large number of photocatalysts,Bi has been widely studied by researchers with high stereoscopic activity for lone pair electrons.In this paper,Bi₁₂TiO₂₀0 was taken as the research target and the theoretical calculation.The experimental test of the Bi₁₂TiO₂₀ and the doped Bi₁₂TiO₂₀ were carried out.The details were as follwes:?1?Study on Bi₁₂TiO₂₀.Based on the primary principle,Bi₁₂TiO₂₀ cell was theoretically simulated and the optical properties were calculated.The theoretical results show that Bi₁₂TiO₂₀ has a suitable band width so it can absorb visible light.Bi₁₂TiO₂₀ samples were prepared by co-precipitation processing.The prepared catalysts were characterized by XRD,SPS,UV-vis and BET.Finally the photocatalytic performance of samples under different preparation conditions was analyzed.The results show that Bi₁₂TiO₂₀ sample can absorb the visible light and have the separation ability of electron and hole in visible light.These are consistent with the results of the simulation.Moreover,Bi₁₂TiO₂₀ has the ability to degrade methyl orange in visible light by the test of photocatalytic properties.?2?Study on La doped Bi₁₂TiO₂₀.Using the CASTEP section of Materials Studio software,we simulated La to replace Bi and to go into the Bi₁₂TiO₂₀ crystal cell.The theoretical value of its forbidden band width,state density and optical properties were simulated.The results show that the replacement of La did not affect the band gap and state density of Bi₁₂TiO₂₀ and the entry of La reduced the band width because of the presence of impurity level in the band width of Bi₁₂TiO₂₀.The La doped Bi₁₂TiO₂₀samples were prepared by ultrasonic assisted method.In this thesis,the concentration of La,the calcination temperature,the ultrasonic power and the ultrasonic time were considered to get the optimal condition.The results show that the doped sample can extend the range of visible absorption and increase the separation ability of electrons and holes.Through the test of photocatalytic properties,the ability of doped samples to degrade methyl orange was improved.?3?Study on N doped Bi₁₂TiO₂₀.In this thesis,the band width,the state density and the optical properties of the N doped Bi₁₂TiO₂₀ sample were theoretically calculated by using the software simulation.The results show that the substitution of N has an impurity level near the top of the valence band of Bi₁₂TiO₂₀,and the band gap decreases.So the range of visible light absorption is widened and the strength is enhanced.N doped Bi₁₂TiO₂₀ photocatalyst was prepared by ultrasonic assisted method.The results show that the doping of N improves the adsorption capacity,broadens the absorption range of visible light and improves the photocatalytic efficiency.