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–N4 active sites have shown immense potential in the oxygen reduction reaction (ORR). However, the limited ability to adsorb O2 and catalyze subsequent O–O bond breaking on Fe–N4 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–N4 active sites, with theoretical calculations, demonstrating that Fe–N4 sites anchored on low–curvature surfaces (lc-Fe-N4) 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–N4 sites, unlocking their potential for extended use in electrocatalytic and energy storage applications.