Unveiling an S-scheme F–Co3O4@Bi2WO6 heterojunction for robust water purification

Abstract

Devising a desirable nano-heterostructured photoelectrode based on the charge transfer kinetics mechanism is a pivotal strategy for implementing efficient photoelectrocatalytic (PEC) technology, since the charge separation and utilization efficiency of a photoelectrode is critical to its PEC performance. Herein, we fabricate a F–Co3O4@Bi2WO6 core–shell hetero-array photoanode by coupling Bi2WO6 nanosheets with F–Co3O4 nanowires using a simple solvothermal solution method. The three-dimensional hierarchical heterostructure has a homogeneous chemical interface, helping it to promote an S-scheme-based carrier transport kinetics and maintain excellent cycling stability. Charge density difference calculations verify the electron migration trend from F–Co3O4 to Bi2WO6 upon hybridization and the formation of an internal electric field in the heterojunction, consistent with the S-scheme mechanism, which is identified by in situ irradiation X-ray photoelectron spectroscopy and by ultraviolet photoelectron spectroscopy. The optimized F–Co3O4@Bi2WO6-2 photoelectrode achieves high carrier utilization efficiency and exhibits superior PEC degradation performance for various organic pollutants, including reactive brilliant blue KN-R, rhodamine B, sulfamethoxazole, and bisphenol A. This work not only reveals that F–Co3O4@Bi2WO6-2 is effective for PEC water remediation but also provides a strategy to enhance carrier transport kinetics by designing binary oxides.