Atomic Cobalt–Silver Dual-Metal Sites Confined on Carbon Nitride with Synergistic Ag Nanoparticles for Enhanced CO2 Photoreduction

Photocatalytic reduction of CO₂ to value-added solar fuels is of great significance to alleviate the severe environmental and energy crisis. Herein, we report the construction of a synergistic silver nanoparticle catalyst with adjacent atomic cobalt-silver dual-metal sites on P-doped carbon nitride (Co₁Ag_(1+n)-PCN) for photocatalytic CO₂ reduction. The optimized photocatalyst achieves a high CO formation rate of 46.82 μmol g_cat^-1 with 70.1% selectivity in solid-liquid mode without sacrificial agents, which is 2.68 and 2.18-fold compared to that of exclusive silver single-atom (Ag₁-CN) and cobalt-silver dual-metal site (Co₁Ag₁-PCN) photocatalysts, respectively. The closely integrated in situ experiments and density functional theory calculations unravel that the electronic metal-support interactions (EMSIs) of Ag nanoparticles with adjacent Ag-N₂C₂ and Co-N₆-P single-atom sites promote the adsorption of CO₂* and COOH* intermediates to form CO and CH₄, as well as boost the enrichment and transfer of photoexcited electrons. Moreover, the atomically dispersed dual-metal Co-Ag SA sites serve as the fast-electron-transfer channel while Ag nanoparticles act as the electron acceptor to enrich and separate more photogenerated electrons. This work provides a general platform to delicately design high-performance synergistic catalysts for highly efficient solar energy conversion.