Dual-molten-salt engineering of accessible active sites in single-atom Fe–N–C catalysts

Abstract

We report a dual-molten-salt (NaCl and KCl) strategy to address the limited accessibility of ZIF-8-derived single-atom sites. This synergy increases the accessible Fe–N_x site density to 4.0 × 10¹⁹ sites g⁻¹ and the utilization to 27%, together with enhanced intrinsic activity for electrocatalytic oxygen reduction.