Correlation of crystal structures and electronic structures and photocatalytic properties of the W-containing oxides

Three W-containing complex oxides Bi2W2O9, Ag2WO4 and AgBiW2O8 were synthesized and their photophysical and photocatalytic properties for H-2 and O-2 evolution were investigated. Compared with WO3 which is unable to evolve H-2 from an aqueous CH3OH solution, Bi2W2O9 and the other two W-containing photocatalysts can evolve H-2 and O-2 from aqueous solutions of sacrificial reagents CH3OH and AgNO3, respectively. Of these oxides, AgBiW2O8 exhibits the highest photo-activity. The results suggest that in these photocatalysts, the bottom of the conduction band has been raised to meet the potential requirements of photocatalytic H-2 evolution. Furthermore, the theoretical calculation and catalysts' characterization show that the crystal field of these materials influences heavily the electronic structures, raising the bottom of the conduction band in all materials. Altogether, this work suggests a feasible way to modify the electronic structure of a semiconductor to realize photocatalytic H-2 and O-2 evolution.