Simultaneously Tailoring Hydrostability and Photoelectroactivity in Heterocluster Metal–Organic Frameworks for Efficient Photocatalytic Hydrogen Production

The simultaneous enhancement of structural stability and photoelectroactivity in metal-organic frameworks (MOFs) remains a critical challenge for sustainable photocatalytic hydrogen (H₂) production. Herein, an atomically-precise heterocluster assembly approach is presented to construct two isostructural 3D MOFs, CuSL-CuX (X = Cl, Br), featuring a cds net. CuSL-CuXs integrate hexanuclear copper-sulfur {Cu₆S₆} cluster and dinuclear copper-halogen {Cu₂X₂} cluster, which not only impart exceptional stability across a broad pH range (1-14) but also enable wide visible-light absorption, tailored redox potentials, and efficient charge-carrier dynamics. Notably, halogen substitution markedly boosts photocatalytic activity: CuSL-CuBr achieves an efficient H₂ evolution rate of 50.28 mmol g^-1 h^-1 without noble metals, doubling that of CuSL-CuCl (26.99 mmol g^-1 h^-1) and surpassing most reported MOF-based photocatalysts. Both experimental and theoretical investigations indicate that bromine substitution optimizes electronic structure, refines orbital distribution, and accelerates charge separation, ultimately leading to promoted photocatalytic efficiency. This research provides insights into the structure-property interplay in heterocluster MOFs and establishes a paradigm for designing robust, high-performance photocatalysts through precise cluster engineering.