Long-range electron synergy over Pt₁-Co₁/CN bimetallic single-atom catalyst in enhancing charge separation for photocatalytic hydrogen production

The development of novel single-atom catalysts with optimal electron configuration and economical noble-metal cocatalyst for efficient photocatalytic hydrogen production is of great importance, but still challenging. Herein, we fabricate Pt and Co single-atom sites successively on polymeric carbon nitride (CN). In this Pt₁-Co₁/CN bimetallic single-atom catalyst, the noble-metal active sites are maximized, and the single-atomic Co₁N₄ sites are tuned to Co₁N₃ sites by photogenerated electrons arising from the introduced single-atomic Pt₁N₄ sites. Mechanism studies and density functional theory (DFT) calculations reveal that the 3d orbitals of Co₁N₃ single sites are filled with unpaired d-electrons, which lead to the improved visible-light response, carrier separation and charge migration for CN photocatalysts. Thereafter, the protons adsorption and activation are promoted. Taking this advantage of long-range electron synergy in bimetallic single atomic sites, the photocatalytic hydrogen evolution activity over Pt₁-Co₁/CN achieves 915.8 mmol·g^-1_Pt·h⁻¹, which is 19.8 times higher than Co₁/CN and 3.5 times higher to Pt₁/CN. While this electron-synergistic effect is not so efficient for Pt nanoclusters. These results demonstrate the synergistic effect at electron-level and provide electron-level guidance for the design of efficient photocatalysts.