Construction of dual Z-scheme Bi2S3/Bi2O3/WO3 ternary film with enhanced visible light photoelectrocatalytic performance

A dual Z-scheme Bi₂S₃/Bi₂O₃/WO₃ ternary film was constructed via a controllable reduction of peroxotungstate by ethanol, calcination of Bi (NO₃)₃ and in situ anion exchange of Bi₂O₃ with sulfide. The as-prepared composite film was characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The UV-visible diffuse reflectance spectroscopic and photoluminescence studies indicated that the introduction of Bi₂S₃ in Bi₂O₃/WO₃ film effectively improved the absorption of the film in the visible region and suppressed the recombination of photogenerated carriers. The photoelectrocatalytic activity of the Bi₂S₃/Bi₂O₃/WO₃ film was evaluated by decoloration of Rhodamine B under visible light illumination. Compared with WO₃ and Bi₂O₃/WO₃ films, the Bi₂S₃/Bi₂O₃/WO₃ film exhibited much higher degradation efficiency. Moreover, the enhanced visible light photoelectrocatalytic activity of the Bi₂S₃/Bi₂O₃/WO₃ film was also demonstrated by efficient degradation of diclofenac. According to the reactive oxygen species detected by electron spin resonance, a dual Z-scheme system formed in the Bi₂S₃/Bi₂O₃/WO₃ film was proposed, which offered a new approach to the construction of semiconducting composite film with high photoelectrocatalytic performance for pollutant removal.