Constructing interfacial charge transfer channels via plasmon-mediated dual excitation in S-vacancy-rich ZnIn₂S₄/CuSe...

Conventional photocatalysts are inherently inefficient at harnessing the predominant near-infrared (NIR) component of sunlight, and their intrinsic kinetic and thermodynamic barriers further impose a severe constraint on solar-to-hydrogen (H₂) conversion efficiency. However, the rational design of highly efficient, durable NIR-responsive photocatalysts that avoid scarce metal cocatalysts and toxic dyes remains a pivotal challenge. Herein, we demonstrate a new strategy for constructing a strong interfacial coupled heterojunction that strategically integrates plasmonic CuSe with S-vacancy-rich ZnIn₂S₄ (Vs-ZnIn₂S₄) to enhance NIR-driven H₂ evolution through a plasmon-mediated dual excitation (PMDE) mechanism. As evidenced by ultrafast femtosecond transient absorption (fs-TA) spectroscopy and density functional theory (DFT) calculations, the rational heterointerface engineering gives rise to fast charge-transfer channels, which in turn lower the reaction energy barrier, suppress carrier recombination, and induce interfacial charge redistribution. These improvements collectively contribute to an optimized heterojunction that achieves an apparent quantum efficiency of 3.0% at 940 nm, surpassing all state-of-the-art noble-metal-free photocatalysts operating beyond 900 nm reported to date. The composite maintains its structural and catalytic integrity even under strong acidic/alkaline conditions (e.g., pH = 1 and pH = 12) and in high-salinity environments (e.g., 5.0 M NaCl solution), setting a benchmark for ultrastable NIR light-harvesting photocatalysts. This work provides novel insights into optimizing charge separation, stabilization, and accumulation during NIR-driven H₂ production via PMDE.