Boosting sunlight-powered photocatalytic fuel cell with S-scheme Bi2WO6/ ZnO nanorod array composite photoanode

Abstract

The construction of intimate contact and effective segregation of charge carrier is a prominent approach to ameliorate the photoactivity of heterojunction catalyst. Herein, a S-scheme flake ball-like Bi2WO6 loaded on ZnO nanorod array (Bi2WO6/ZnO NRA) composite photoanode has been fabricated via a two-step electrochemical-hydrothermal technique and utilized in a sunlight-powered photocatalytic fuel cell (PFC) for the first time. Incorporation of Bi2WO6 can prolong the visible light response range and improved the electrochemical traits of the composite photoanode. The photoelectric test and chemical oxidation demand (COD) measurement on municipal wastewater treatment have been entirely recorded under direct sunlight. The maximum power density of the Bi2WO6/ZnO NRA was 2.707 mu W/cm(2), which was 1.8 times than that of the pure ZnO NRA in treating municipal wastewater. The COD removal efficiency of municipal wastewater using 2-Bi2WO6/ZnO NRA PFC was 100% over 180 min period. The boosted photoactivity of the composite was accredited to the one-dimensional nanorod array morphology and the formation of S-scheme heterojunction structure between the Bi2WO6 and ZnO NRA, which tremendously segregated charge and retained high redox potential. The postulated S-scheme mechanism was supported by the radical quenching test and Mott-Schottky analyses. Consistent photocatalytic performance of Bi2WO6/ZnO NRA photoanode was also found after five cyclic runs. This work sheds light on the potential applications of efficient sunlight-activated catalysts in water decontamination and energy recovery.