Cu(II) as a General Cocatalyst for Improved Visible-Light Photocatalytic Performance of Photosensitive Ag-Based Compounds

Usually, cocatalyst modification of photocatalysts is an efficient approach to enhance the photocatalytic performance by promoting effective separation of photogenerated electrons and holes. It is highly required to explore new and effective cocatalysts to further enhance the photocatalytic performance of photocatalytic materials. In the present work, Cu­(II) cocatalyst was successfully loaded on the surface of various Ag-based compounds (such as AgCl, Ag₃PO₄, AgBr, AgI, Ag₂CO₃, and Ag₂O) by a simple impregnation route, and their photocatalytic activity of Cu­(II)/Ag-based photocatalysts was evaluated by the photocatalytic decolorization of methyl orange and photocatalytic decomposition of phenol solution under visible-light illumination. As one of the typical photosensitive Ag-based compounds, the photocatalytic activity of AgCl could be greatly improved by optimizing the amount of Cu­(II) cocatalyst, and the highest photocatalytic performance of the resulted Cu­(II)/AgCl was higher than that of the unmodified AgCl by a factor of 2.1. Significantly, the Cu­(II) was demonstrated to be a general and effective cocatalyst to improve the visible-light photocatalytic performance of other various photosensitive Ag-based compounds (such as AgBr, AgI, Ag₃PO₄, Ag₂CO₃, and Ag₂O) in addition to the AgCl photocatalyst. Based on the present results, it is proposed that the Cu­(II) cocatalyst functions as electron scavengers to quickly capture photogenerated electrons from the excited photocatalysts and then works as reduction active sites to reduce O₂ effectively, resulting in an effective separation of photogenerated electrons and holes. Compared with the expensive noble metal cocatalyst (such as Pt, Au, and Pd), the present promising Cu­(II) cocatalyst can be considered to be one of the perfect cocatalysts for the smart preparation of various highly efficient photocatalysts in view of its abundance and low cost.