Quantum‐Corrected Plasmonic Effect of Au ₂₅ Clusters Regulates Adsorption Behaviors for Boosted Photocatalytic Overall Water Splitting

Plasmonic‐assisted solar‐driven photocatalytic water splitting for hydrogen production represents a sustainable strategy for green energy generation. However, conventional plasmonic enhancement via photo‐induced electron injection into water molecules faces a key limitation: weak interfacial H 2 O adsorption characterized by restriction solely to H‐atom‐mediated interactions, which severely constrains reaction kinetics. Simultaneously, the novel quantum‐corrected plasmonic effect could improve the electron models in optoelectronic device; however, within the domain of photocatalytic water splitting, experimental validations of this effect remain relatively scarce. Here, we harness the quantum‐corrected plasmonic effect via Au 25 nanocluster incorporation to realize and enhance photocatalytic overall water splitting performance, facilitated by modulated surface adsorption behavior through electron‐deficient Au δ+ active sites originating from the size effect and interband transitions. In this case, the Au δ+ active sites enhance the antibonding‐orbital occupancy of adsorbed Au‐O species, accelerating both multipath electron injection and the activation process of water molecules, ultimately facilitating the cleavage of H─O bonds. Consequently, it achieves H 2 and O 2 evolution rates of 1.07 and 0.54 mmol h −1 under light irradiation with catalyst ZnIn 2 S 4 ‐Au 25 , resolving the long‐standing challenge of incomplete overall water splitting for sole Au nanoparticle‐decorated photocatalysts, providing a promising strategy for photocatalytic overall water splitting and new insights into designing nanocluster‐based photocatalysts.