Photocatalytic water splitting by band-gap engineering of solid solution Bi1−xDyxVO4 and Bi0.5M0.5VO4 (M = La, Sm, Nd, Gd, Eu, Y)

Abstract

A series of metal oxide solid solutions Bi1−xDyxVO4 and Bi0.5M0.5VO4 (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. Bi1−xDyxVO4 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. Bi1−xDyxVO4 solid solutions of tetragonal type could split water into H2 and O2 simultaneously when loaded with 0.3wt% Pt and 1wt% Pt-Cr2O3 respectively as cocatalyst. Among these catalysts, Bi0.5Dy0.5VO4 showed the best photocatalytic activity for water splitting under UV light irradiation. Besides, Bi0.5M0.5VO4 (M=La, Sm, Nd, Gd, Eu, Y) were also prepared and discovered to be of tetragonal type as same as Bi0.5Dy0.5VO4. They performed high photocatalytic activities of splitting pure water into H2 and O2 under UV light irradiation when loaded with 1wt% Pt-Cr2O3. The activities of Bi0.5M0.5VO4 (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.