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

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.