Mechanistic Insight into the Synergy between Platinum Single Atom and Cluster Dual Active Sites Boosting Photocatalytic Hydrogen Evolution

In the energy transition context, the design and synthesis of high-performance Pt-based photocatalysts with low Pt content and ultrahigh atom-utilization efficiency for hydrogen production are essential. Herein, a facile approach for decorating atomically dispersed Pt cocatalysts having single-atom (SA) and atomic cluster (C) dual active sites on CdS nanorods (Pt_SA+C/CdS) via atomic layer deposition is reported. The size of the cocatalyst and the spatial intimacy of the cocatalyst active sites are precisely engineered at the atomic scale. The Pt_SA+C/CdS photocatalysts show the optimized photocatalytic hydrogen evolution activity, achieving a reaction rate of 80.4 mmol h⁻¹ g⁻¹, which is 1.6- and 7.3-fold higher than those of the Pt_SA/CdS and Pt_NP/CdS photocatalysts, respectively. Thorough characterization and theoretical calculations reveal that the enhanced photocatalytic activity is due to a remarkable synergy between SAs and atomic clusters as dual active sites, which are responsible for water adsorption–dissociation and hydrogen desorption, respectively. A similar synergetic effect is found in a representative Pt/TiO₂ system, indicating the generality of the strategy. This study demonstrates the significance of the synergy between active sites for enhancing the reaction efficiency, opening a new avenue for the rational design of atomically dispersed photocatalysts with high efficiency.