Self-Supported ZnWO₄/WO₃ Photoelectrodes for Photoelectrocatalytic Degradation of Ciprofloxacin Pollutants

A self-supported ZnWO₄/WO₃ photoelectrode was fabricated using a simple two-step strategy involving anodic oxidation and chemical drop-casting. Compared to the pristine WO₃ photoelectrode, the ZnWO₄/WO₃ composite exhibited significantly enhanced visible-light absorption and improved photogenerated charge separation efficiency. Under simulated solar irradiation and a bias voltage of 0.6 V, the ZnWO₄/WO₃ photoelectrode achieved 80.0% degradation efficiency for ciprofloxacin within 120 min. These performance enhancements originate from the formation of a Z-scheme heterojunction at the ZnWO₄/WO₃ interface. In this heterojunction, electrons in the conduction band of WO₃ combine with holes from the valence band of ZnWO₄, leaving electrons with a more negative potential in the conduction band of ZnWO₄ and holes with a more positive potential in the valence band of WO₃. This synergistic mechanism promotes efficient participation of photogenerated electrons and holes in photoelectrocatalytic degradation reactions