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

Abstract

Three W-containing complex oxides Bi₂W₂O₉, Ag₂WO₄ and AgBiW₂O₈ were synthesized and their photophysical and photocatalytic properties for H₂ and O₂ evolution were investigated. Compared with WO₃ which is unable to evolve H₂ from an aqueous CH₃OH solution, Bi₂W₂O₉ and the other two W-containing photocatalysts can evolve H₂ and O₂ 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 H₂ 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 H₂ and O₂ evolution.