Hydrogen Migration Enhances Proton-Coupled Electron Transfer in an S-Scheme Heterojunction for High-Efficiency Photocatalysis

Abstract

The kinetic bottleneck in solar-driven hydrogen evolution lies in the slow proton and electron delivery, which severely limits the efficiency of proton-coupled electron transfer (PCET). To address this, we report a bioinspired dual-channel strategy using a CdIn₂S₄/Ni(OH)₂ (CIS/NOH) heterojunction. An S-scheme charge-transfer pathway is constructed to spatially separate strong reductants and oxidants, directing electrons to NOH for H₂ evolution and holes to CIS for benzyl alcohol oxidation. More critically, an interfacial hydrogen adsorption energy gradient drives directional proton migration from CIS to NOH, enriching protons precisely at the electron-accumulation sites. This synergy of vectorial electron flow and proton migration co-localizes reactants, dramatically accelerating the PCET process. The optimal catalyst achieves remarkable concurrent production of H₂ (17.96 mmol g^–1 h^–1) and benzaldehyde (12.63 mmol g^–1 h^–1). This work provides a novel blueprint for designing artificial photosynthetic systems by simultaneously managing charge and mass transport.

Keywords

CdIn₂S₄/Ni(OH)₂ / interfacial hydrogen migration / photocatalysis / proton-coupled electron transfer / S-scheme heterojunction

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