A facile and green large-scale fabrication of single atom catalysts for high photocatalytic H2 evolution activity

Atomically dispersed metal catalysts, which have maximized atom utilization efficiencies, have demonstrated high activities for the Hydrogen evolution reaction (HER). However, there is a lack of simple strategies for the preparation of Single-atom catalysts (SACs). Herein, we report a clean and robust electrochemical method for synthesizing a series of SACs. This methodology employs a Carbon nitride (CN) suspension in pure water as a bath solution and a pure metal target as an easily removable precursor instead of a strong ionic electrolyte. The simplicity of this system facilities the large-scale production and direct use of SACs without any subsequent processing. The mass loading of metal atoms is precisely adjusted using the applied electric field intensity and the processing time. We demonstrate the atomic dispersion and the coordination structure of metal atoms in the prepared SACs using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy. The experimental results show that the Ag1/CN SAC exhibits a higher HER activity than that of Pt nanoparticles on CN, even at low mass loadings. For instance, based on metal loading, Ag1/CN exhibits a record-high photocatalytic HER rate of 1688.9 mmol h−1 g−1metal, much higher than that of Pt nanoparticles (328.5 mmol h−1 g−1metal), which confirms the super-high utilization efficiency of Ag atoms. Density functional theory calculations and experiments suggest that this high photocatalytic activity was attributable to a reduced H2 evolution barrier, good proton adsorption and H2 desorption properties. This work provides a novel approach for the synthesis of durable SACs with excellent photocatalytic activities.