Atomically Dispersed Cu–Ni Dual-Metal Sites on g-C₃N₄ for Synergistic Enhancement of Photocatalytic Hydrogen Evolution

Single-atom catalysts (SACs) offer a promising strategy to enhance light utilization and charge carrier dynamics in photocatalytic hydrogen evolution. However, the uniform dispersion and stabilization of single-atom active sites remain significant challenges. Herein, we report the fabrication of atomically dispersed Cu and Ni dual-metal sites anchored on graphitic carbon nitride (CuNi–g-C3N4), achieving an outstanding hydrogen evolution rate of 1275 μmol g–1 h–1 under visible light irradiation. The synergistic interaction between Cu and Ni bimetallic dual-atom catalysts (DACs) modulates the electronic structure of g-C3N4, creating active sites and suppressing charge recombination, as confirmed by density functional theory (DFT) calculations. X-ray absorption spectroscopy (XAS) analysis verifies the atomic dispersion of the Cu and Ni sites, revealing their interactions with the carbon nitride framework. Photoluminescence (PL) spectroscopy and electrochemical impedance spectroscopy (EIS) further demonstrate enhanced charge separation and reduced recombination in CuNi–g-C3N4. The catalyst exhibits excellent stability and maintains its photocatalytic activity over multiple reaction cycles, underscoring the potential of DACs for sustainable hydrogen production. This study provides insights into the rational design of dual single-atom catalysts for the efficient conversion of solar energy to hydrogen.