Preparation of BiOCl-(NH4)3PW12O40 Photocatalyst and a Mechanism for Photocatalytic Degradation of Organic Pollutants

Abstract

The separation efficiency of photogenerated electrons and holes is the key to photocatalytic performance. Layered BiOCl is a kind of newly exploited efficient photocatalyst, but its wide-spread practical application is hindered by the rapid recombination of photogenerated electron-hole pairs and low quantum efficiency. In this study, we prepared a composite photocatalyst via a hydrothermal method in which (NH4)3PW12O40 (NH4PTA) is the acceptor of photoelectrons from BiOCl. The photocatalytic performance of variants of BiOCl-NH4PTA was evaluated by the removal efficiency of methyl orange (MO). The experimental results showed that the BiOCl-NH4PTA[n (Bi):n (W)=1:1] had the best photocatalytic activity under the irradiation of sunlight simulated by xenon light. The photocatalytic mechanism was investigated using the reactive species trapping experiments. It was found that MO could be photodegraded by,·OH, and holes over BiOCl. Differently, and·OH were the dominant reactive species for the reactions over the composite photocatalyst. It was proved that NH4PTA was the acceptor of photoelectrons by the XPS on the photocatalyst before and after reaction. The photocurrent test verified the superior photocatalysis of BiOCl-NH4PTA which was attributed to the efficient separation of electron-hole pairs.