Wenjing Tang

Constructing efficient charge separation pathways remains a crucial challenge for advancing photocatalytic hydrogen evolution. In this work, a Ni₂P/CdIn₂S₄/In₂S₃ (NP/CIS/IS) heterostructure featuring S-scheme charge separation and multiple electron transfer pathways was constructed through a stepwise assembly approach. Work function analysis, combined with in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) and density functional theory (DFT) calculations, confirmed the formation of a built-in electric field (BIEF) that drives directional carrier migration across the CIS/IS interface, establishing a typical S-scheme heterojunction. Electron paramagnetic resonance (EPR) studies further revealed significantly enhanced redox activity in the CIS/IS-3 system, attributed to the efficient spatial separation of photogenerated charges. The incorporation of NP nanoparticles remarkably boosted the visible-light-driven hydrogen evolution performance (λ ≥ 420 nm), achieving a high rate of 45,057.1 μmol g^-1 h^-1. This enhancement arises from the dual role of NP as the active site and electron mediator, facilitating charge extraction, lowering the Gibbs free energy for H₂ formation, and accelerating hydrogen desorption. Furthermore, three-dimensional charge density mapping validated the presence of multiple synergistic charge transport channels within the 5.7%NP/CIS/IS-3 composite. This study provides new insights into the design of advanced heterostructured photocatalysts for efficient, sustainable hydrogen production from solar energy.