Modulating interfacial electric field in oxygen-defect-mediated S-scheme Mo-ZnIn2S4/BiOCl heterostructures for efficient photocatalytic hydrogen evolution

Abstract

The inefficient separation and migration of photogenerated charges remain a primary obstacle for photocatalytic hydrogen evolution. Herein, a novel oxygen-defect-mediated S-scheme heterojunction of Mo-ZnIn2S4/BiOCl (Mo-ZIS/BOC) was constructed for efficient production of hydrogen using visible light. The introduction of Mo species not only optimizes the electron structure of ZnIn2S4 but, more importantly, effectively modulates the interfacial electric field (IEF) at the heterojunction interface. The optimum Mo-ZIS/BOC catalyst exhibits an impressive hydrogen evolution rate of 18.16 mmol g⁻¹ h⁻¹, which is 11.9 times higher than that of pure ZnIn2S4 and also surpasses the undoped ZIS/BOC heterojunction. The high activity and excellent stability of Mo-ZIS/BOC were attributed to the enhanced IEF and oxygen-defect-mediated S-scheme pathway, significantly promoting directional charge transfer and separation. Combined with photoelectrochemical characterizations and theoretical calculations, the mechanism of Mo in modulating the IEF and the charge transfer pathway was elucidated. This work offers profound insights into how elemental doping can intensify the IEF of S-scheme heterojunctions for advanced solar energy conversion.