Hydrogen passivation stabilizes edge-located single-atom metal sites for electrocatalysis

Single-atom catalysts (SACs) supported on nitrogen-doped carbon have emerged as promising precious-metal-free electrocatalysts. However, their practical application is often hindered by insufficient stability. Particularly, SACs with edge-located metal sites, although benefiting from high intrinsic activity associated with their coordinatively unsaturated edge structure, are highly susceptible to electrochemical carbon corrosion, leading to rapid performance degradation. Here, we propose hydrogen passivation of edge carbon as a universal and effective strategy to stabilize edge-located active sites in SACs. Through extensive first-principles calculations, we elucidate the formation mechanism and representative atomic configurations of edge-located single-atom metal sites, including Fe, Co, and Ni. Based on computed Pourbaix diagrams, we identify the origin of their instability and clarify the role of hydrogen passivation in suppressing both carbon and nitrogen etching at vulnerable edge regions. Using the oxygen reduction as a representative electrocatalytic process, combined theoretical and experimental investigations, including in situ/operando characterization, further demonstrate that the synergistic integration of edge-located active sites with hydrogen-passivated edge carbon simultaneously enhances catalytic activity and durability, overcoming the conventional activity–durability trade-off in SACs. The practical potential is validated in zinc–air batteries, where the optimized SAC achieves a peak power density of 312.45 mW cm⁻² and sustains stable operation for over 1500 hours.