Dependence of metallic Ag on the photocatalytic activity and photoinduced stability of Ag/AgCl photocatalyst

Abstract

Recently, Ag/AgCl has been demonstrated to be a stable and highly efficient photocatalytic material. However, considering the strong photosensitive property of AgCl phase without Ag, it is clear that the metallic Ag plays an important role on the photoinduced stability of Ag/AgCl composite, which has a great effect on its photocatalytic performance. In this study, the Ag/AgCl photocatalysts with different amounts of metallic Ag were prepared by a facile hydrothermal method (30–160°C) to reveal the dependence of metallic Ag on the photoinduced stability and photocatalytic activity of Ag/AgCl photocatalyst. It was found that the amounts of metallic Ag in the Ag/AgCl could be easily controlled by adjusting the hydrothermal temperature, and the Ag amounts (0–9.8at%) gradually increased with the hydrothermal temperature from 30 to 160°C. Photocatalytic results indicated that the metallic Ag had a great effect on the photoinduced stability and photocatalytic activity of Ag/AgCl photocatalysts. As for the AgCl-30 photocatalyst (without metallic Ag), with increasing repetitions of photocatalytic reactions, the photocatalytic performance firstly decreased owing to the rapid increase of metallic Ag via the reduction of lattice Ag+ on AgCl surface, while the subsequently stable performance corresponded to the formation of a stable Ag–AgCl composite structure. For the Ag/AgCl (160°C) photocatalyst, the sample always exhibited a comparable and stable photocatalytic performance due to the initial existing of some metallic Ag (ca. 9.8at%). Therefore, a certain amount of metallic Ag on the AgCl surface can greatly improve the photoinduced stability of Ag/AgCl photocatalyst in addition to maintaining its stable photocatalytic activity.