Highly enhanced photocatalytic activity of WO3 thin films loaded with Pt–Ag bimetallic alloy nanoparticles

Abstract

WO₃ thin films loaded with Pt–Ag bimetallic alloy nanoparticles were successfully synthesized by a three-step method involving the formation of a homogeneous precursor sol, spin coating as well as UV-light reduction, and calcination. Moreover, a systematic, comparative study of the microstructure, chemical environment and electrochemical characteristics of the as-prepared Pt/WO₃, Ag/WO₃, and Pt–Ag/WO₃ thin films was carried out. It was found that the Pt–Ag/WO₃ thin film exhibited a highly enhanced photocatalytic performance for the degradation of methylene blue solution compared with the pure WO₃, Pt/WO₃ and Ag/WO₃ thin films. Based on the experimental results and the energy-band diagrams, the transfer paths of photogenerated charges and the enhanced photocatalytic mechanism were proposed. It was suggested that the photogenerated electrons from the conduction band of WO₃ first transferred to Ag and then to Pt in the Pt–Ag/WO₃ sample during the photocatalytic process, promoting the efficient two-electron reduction of O₂ compared to in the Pt/WO₃ and Ag/WO₃ samples. In addition, this process prevented the oxidation of Ag in the Pt–Ag/WO₃ sample during the photodegradation process in air. Overall, this study provides a novel approach to design efficient photocatalysts decorated by bimetallic alloy nanoparticles.