Abstract: The development of efficient photocatalytic systems for simultaneous hydrogen production and organic synthesis remains a significant challenge, primarily due to slow charge kinetics and limited light absorbance. In this paper, we overcome these limitations by engineering a lattice-matched NiCo₂S₄@Zn_0.5Cd_0.5S (NCS@ZCS) heterostructure at the atomic level. This system synergistically combines photothermal effects with coherent interfacial charge transfer. The precisely tuned heterointerface (lattice mismatch δ = 1.6%) forms an Ohmic contact that generates a strong built-in electric field, enabling ultrafast electron transfer and suppressing recombination. The metallic NCS cocatalyst plays a dual role: enhancing proton reduction kinetics (ΔG_H* = 0.09 eV) and producing localized photothermal heating to overcome reaction barriers. This integrated design delivers outstanding performance in coupled photocatalytic reactions, achieving a hydrogen evolution rate of 92.9 mmol g^âˆ'1h^âˆ'1, benzaldehyde selectivity of 96%, and an apparent quantum efficiency of 9.1% at 400 nm. Our findings demonstrate how precise interface engineering can address fundamental limitations in charge separation, transport, and surface reactivity, advancing solar-driven chemical synthesis.

Key words: Lattice-matched heterojunction, Photothermal photocatalysis, Zn_0.5Cd_0.5S, NiCo₂S₄, Solar-to-chemical conversion