Photocatalytic activity of Ag₂MO₄ (M = Cr, Mo, W) photocatalysts

Ag-containing semiconductors have attracted significant attention because of their unique photosensitivity that provides these materials with visible-light photocatalytic activity. This study systematically investigates the correlation among the photophysicochemical performance, crystal structure, electronic structure, and photocatalytic activity and stability of three Ag-containing photocatalysts Ag₂MO₄ (M = Cr, Mo, W) prepared by microemulsion based on experimental and theoretical results. The results showed that the photocatalytic activity and stability of the three photocatalysts strongly depend on the light absorption performance of these photocatalysts. Ag₂CrO₄ had the best light absorption performance, exhibiting the highest photocatalytic activity for methylene blue degradation under visible-light irradiation that is 3.5 and 1.5 times that of Ag₂MO₄ and Ag₂WO₄, respectively. Meanwhile, the photocatalytic stability followed the same light absorption performance order. The theoretical calculation showed that a stronger crystal field and a smaller Ag–O distance lower the conduction band bottom of Ag₂CrO₄ and Ag₂WO₄, respectively. This reduction in the conduction band caused the band gap, light-absorption, and subsequent photocatalytic activity and stability of these photocatalysts to differ. The present work contributes to deeply understand and feasibly construct Ag-containing photocatalysts with high photocatalytic activity. © The Royal Society of Chemistry 2015.