Unlocking Efficient Direct Charge Transfer of Ni–N Bridge 2D N-ZnIn₂S₄/Ni Single-Atom Photocatalysts for Hydrogen Evolution

This study reports a strategy for constructing highly efficient single-atom photocatalysts through the formation of Ni-N chemical bonds. By anchoring Ni single atoms on nitrogen-doped ZnIn₂S₄ (N-ZIS), we created a localized charge region that enables directed interfacial charge transfer. The newly formed Ni-N bond plays dual roles of significantly enhancing charge carrier separation and prolonging their lifetime, and serving as an efficient electron transfer pathway from N trap states to Ni active sites. Combined experimental characterization and density functional theory (DFT) calculations confirm the unique stabilizing effect of single Ni atoms in the N-ZIS matrix and elucidate the charge transfer mechanism through Ni-N bridges. The optimized 5%Ni-N30-ZIS photocatalyst exhibits exceptional hydrogen evolution performance, surpassing most previously reported ZIS-based systems. This work highlights the crucial importance of precise control over interfacial chemical bonding at the molecular level for achieving efficient spatial charge separation in inorganic photocatalysts, providing insights for the design of high-performance photocatalytic materials.