Photocatalytic water splitting by band-gap engineering of solid solution Bi_(1-x)Dy_xVO_4 and Bi_(0.5)M_(0.5)VO_4 (M = La, Sm, Nd, Gd, Eu, Y)

摘要

A series of metal oxide solid solutions Bi_(1-x)Dy_xVO_4 and Bi_(0.5)M_(0.5)VO_4 (M = La, Sm, Nd, Gd, Eu, Y) were synthesized by solid state reaction at high temperature and characterized by XRD, UV-vis DRS, BET, SEM. Bi_(1-x)Dy_xVO_4 showed two crystal structures with the component content. For 0.3 <=x<=1.0, the structure was tetragonal type, while that was monoclinic when x=0. For 0.1 <=x<0.3, tetragonal and monoclinic structures had been observed. Bi_(1-x)Dy_xVO_4 solid solutions of tetragonal type could split water into H_2 and O_2 simultaneously when loaded with 0.3 wt% Pt and 1 wt% Pt-Cr_2O_3 respectively as cocatalyst. Among these catalysts, Bi_(0.5)Dy_(0.5)VO_4 showed the best photocatalytic activity for water splitting under UV light irradiation. Besides, Bi_(0.5)M_(0.5)VO_4 (M = La, Sm, Nd, Gd, Eu, Y) were also prepared and discovered to be of tetragonal type as same as Bi_(0.5)Dy_(0.5)VO_4. They performed high photocatalytic activities of splitting pure water into H_2 and O_2 under UV light irradiation when loaded with 1 wt% Pt-Cr_2O_3. The activities of Bi_(0.5)M_(0.5)VO_4 (M=Dy, la, Sm, Nd, Gd, Eu, Y) solid solutions indicated band-gap engineering of metal oxide solid solutions was the feasible method to obtain a photocatalyst for overall water splitting.