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-1Pt·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.