Reversibly tuning the surface state of Ag via the assistance of photocatalysis in Ag/BiOCl

Silver (Ag) nanoparticles can be spontaneously oxidized and present in different oxidized surface phases. The impact of oxidation induced photo absorption property and related photocatalytic activity are still unclear in Ag-decorated semiconductor photocatalysts. Herein, Ag-decorated BiOCl with the metallic Ag0 to oxidized Ag+ were employed to investigate the effect of surface state of Ag on relative photocatalyst properties. A redshift of localized surface plasmon resonance was observed as the Ag0 oxidized to Ag+ and a reversible manipulation was realized in UV light-driven photocatalysis. It is found that the Ag0/BiOCl presents higher photocatalytic activity than Ag+/BiOCl, but this difference is gradually decreasing under UV light irradiation compared with visible light irradiation. A controlled experiment suggests that the reduction of Ag+ under UV light reduced the difference between Ag0/BiOCl and Ag+/BiOCl. The possible mechanism for electron transport and the conversion between Ag+ and Ag0 via the assistance of the photoelectric effect from BiOCl has been elucidated. This photocatalytic reaction assisted reversible tuning the surface state of Ag/BiOCl will open up the possibility of rationally designing Ag-decorated semiconductors for light harvesting.