Unraveling the pH-Dependent Oxygen Reduction Performance on Single-Atom Catalysts: From Single- to Dual-Sabatier Optima

Metal–nitrogen–carbon (M–N–C) single-atom catalysts (SACs) have emerged as a potential substitute for the costly platinum-group catalysts in oxygen reduction reaction (ORR). However, several critical aspects of M–N–C SACs in ORR remain poorly understood, including their pH-dependent activity, selectivity for 2- or 4-electron transfer pathways, and the identification of the rate-determining steps. Herein, by analyzing >100 M–N–C structures and >2000 sets of energetics, we unveil a pH-dependent evolution in ORR activity volcanosfrom a single peak in alkaline media to a double peak in acid... Mehr ...