A Z-scheme WO3 loaded-hexagonal rod-like ZnO/Zn photocatalytic fuel cell for chemical energy recuperation from food wastewater treatment

Abstract

An anodic WO3-loaded on hexagonal rod-like ZnO/Zn (WO3/ZnO/Zn) with the Z-scheme structure was first developed, and employed in a sunlight-powered photocatalytic fuel cell (PFC). Incorporation of WO3 can extend the optical response range and boosted electrical conductivity of composite. Both the photoelectric and mineralization performance in degrading sunset yellow (SSY) and phenol as food wastewaters have been systematically tested under sunlight irradiation. The maximum power density (Pmax) of the WO3/ZnO/Zn PFC was 0.1052 μW cm−2 and 0.0574 μW cm−2, which was 1.86 times and 1.85 times that of the pristine ZnO/Zn PFC in degrading SSY and phenol, respectively over 240 min period. The carbon oxygen demand (COD) removal of SSY and phenol using the WO3/ZnO/Zn PFC was 84.6% and 67.5%, respectively. The enhanced Z-scheme WO3/ZnO/Zn PFC could be ascribed to improved electron transfer via the hexagonal rod-like structure and efficient charge separation, and thereby maintained high redox ability for photoelectrochemical activity. Additionally, active species trapping and hydroxyl radical generation assays supported the Z-scheme photocatalytic mechanism. Intermediates identification results showed an obvious decomposition effect towards both organic molecules. The WO3/ZnO/Zn PFC performance had also investigated in treating actual food wastewater, 63.6% COD was removed and generated 0.498 μW cm−2Pmax output.