Photocatalytic degradation of dyes by AgIO3 under visible light irradiation

AgIO3 was prepared by an ion-exchange method at room temperature. As AgIO3 is a wide bandgap photocatalyst only activated by UV irradiation, the photocatalytic activity of AgIO3 under visible light irradiation occurred by a dye sensitization mechanism. Electron transfer from the excited state of dye molecules to the conduction band (CB) of AgIO3 was allowed for reactive orange 16 (RO) and eosin yellow (EY). Therefore, AgIO3 degraded RO and EY under visible light irradiation. In contrast, AgIO3 showed low activity for degrading methylene blue (MB) and crystal violet (CV) because electron transfer from their excited states to the CB of AgIO3 was not thermodynamically favored. However, during the degradation process of RO or EY using AgIO3, a small amount of metallic Ag was generated on the surface of AgIO3. This new product, Ag/AgIO3, exhibited the capability to degrade MB and CV under visible light irradiation.