Surface curvature effect on single-atom sites for the oxygen reduction reaction: A model of mesoporous MOF-derived carbon

Iron-based single-atom catalysts (Fe-SACs) containing Fe–N 4 active sites have shown immense potential in the oxygen reduction reaction (ORR). However, the limited ability to adsorb O 2 and catalyze subsequent O–O bond breaking on Fe–N 4 sites has hindered their full potential, especially in acidic electrolytes. Here, we present an approach by utilizing a tunable curved surface to enhance the activity of Fe–N 4 active sites, with theoretical calculations, demonstrating that Fe–N 4 sites anchored on low–curvature surfaces (lc-Fe-N 4 ) is favirable for ORR. Experimental results show that the catalyst exhibits excellent catalytic activity and stability for ORR in acidic electrolytes, with a half-wave potential of 0.82 V vs. RHE, approaching that of commercial Pt/C. This work develops an approach for promoting the catalytic activity by anchoring atomically dispersed Fe–N 4 sites, unlocking their potential for extended use in electrocatalytic and energy storage applications.