Cryo‐Electrochemical Deposition of Gold Single Atoms on <i>G</i> ‐C ₃ N ₄ for Photoelectrochemical Water Reduction

Abstract The pursuit of sustainable energy has intensified the exploration of hydrogen as a clean energy carrier, with photoelectrocatalytic water reduction emerging as a green approach to harness solar energy. Graphitic carbon nitride ( g ‐C 3 N 4 ), recognized for its stability and non‐toxicity, presents limitations in photoconversion efficiency due to rapid electron‐hole recombination and narrow light absorption range. To address these challenges, herein, a cryo‐electrochemical deposition strategy is introduced to synthesize g ‐C 3 N 4 loaded with gold single‐atom catalysts (Au 1 ), enhancing charge separation and light absorption. The atomic dispersion of Au 1 on g ‐C 3 N 4 significantly elevates photoelectrocatalytic hydrogen production, achieving a record yield rate on the Au 1 (14.5%)/ g ‐C 3 N 4 sample. Density functional theory (DFT) calculations and comprehensive characterizations reveal the role of Au 1 in modulating the electronic structure and improving charge carrier dynamics. The findings underscore the potential of single‐atom catalysis in advancing photoelectrocatalytic water reduction systems for solar energy conversion and clean energy production.