Atomically Dispersed Silver-Cobalt Dual-Metal Sites Synergistically Promoting Photocatalytic Hydrogen Evolution

Regulating the coordination environment of single-atom sites is of high necessity to promote the catalytic performances of the photocatalysts. Herein, the preparation of atomically dispersed Co-Ag dual-metal sites anchored on P-doped carbon nitride (Co1Ag1-PCN) via supramolecular and solvothermal approaches is reported, which demonstrates desirable performance for photocatalytic H-2 evolution from water splitting. The optimal Co1Ag1-PCN catalyst achieves a remarkable hydrogen production rate of 1190 mu mol g(-1) h(-1) with an apparent quantum yield (AQY) of 1.49% at 365 nm, superior to most of the newly reported metal-N-coordinated photocatalysts. Systematic experimental characterizations and density functional theoretic studies attribute the enhanced photocatalytic activity to the synergistic effect of Co-Ag dual sites with exclusive coordination configuration of Co-N-6 and Ag-N2C2, which enhances the charge density and promotes oriented electrons transport to the metal centers with reduced free energy barriers by facilitating the formation of H* intermediates as the key step in hydrogen evolution. This study reveals a versatile strategy to tailor the electronic structures of dual-metal sites with synergies by engineering the neighboring coordination environment.