<p>Photocatalytic hydrogen production is fundamentally limited by inefficient charge separation and the asynchronous supply of electrons and protons to active sites. Herein, we designed a ZnIn₂S₄/ZnCo₂S₄ (ZIS/ZCS) heterojunction with an atomically coherent interface achieved via an ultralow lattice mismatch of 0.05%. This unique structure promotes rapid electron transfer through a built-in electric field and facilitates continuous proton migration via a hydrogen spillover effect, thereby synchronizing electron and proton delivery at the catalytic interface. This dual regulation of electrons and protons synergistically promotes protoncoupled electron transfer, resulting in a high hydrogen evolution rate of 70.3 mmol g⁻¹ h⁻¹ and selective oxidation of benzyl alcohol to aldehyde (39.3 mmol g⁻¹ h⁻¹) with 93.6% selectivity. This work demonstrates the critical importance of lattice match and dual charge-proton management in designing efficient photocatalysts for complex redox reactions.</p>