Employing Dilute Bimetallic Dispersion on Nano-Photocatalysts for Enhanced Green Hydrogen Production Under Visible Light.

Photocatalytic water splitting offers a sustainable pathway for producing clean H fuel. However, conventional heterojunction photocatalysts face severe challenges, including diminished redox potential due to complex band alignments, interfacial defects accelerating charge recombination, and long charge-carrier paths reducing photocarrier and material utilization. Here, we achieve efficient, visible-light-driven H generation by employing a dilute bimetallic dispersion on a metal chalcogenide nano-photocatalyst. Using CdS nanorod as a model photocatalyst, we strategically position Cu in lattice sites and Co in interstitial locations to preserve CdS's strong optical properties and redox potential. In this design, Cu species serve as electron sinks to drive H evolution, while the Co/Co couple functions as a redox shuttle to efficiently channel photogenerated holes to the reactant. This optimized photocatalyst demonstrates a high H production rate of ≈52 mmol g h, surpassing bare CdS and other emerging photocatalytic designs by >100-fold and >65-fold, respectively. Mechanistic studies highlight the roles of Cu and Co as electron and hole sinks and active redox sites, thereby facilitating directed photocarrier migration and enhanced light-to-chemical conversion. By establishing spatially distinct redox sites, this work provides a foundational framework for designing next-generation photocatalytic platforms, paving the way for sustainable energy and chemical applications using light.