LAUSR

Abstract Oxygen reduction reaction is a critical process at the cathode of proton-exchange membrane fuel cells and metal–air batteries. Carbon-based single metal atom nanocomposites have emerged as effective alternatives to state-of-the-art platinum catalysts, in which the electrocatalytic activity is attributed largely to the formation of metal–nitrogen coordination moieties (MNx) within the carbon matrix. In this review, we summarize recent progress in the studies of metal and nitrogen codoped carbon as single-atom catalysts toward oxygen reduction reaction within the context of the atomic configuration of the MNx active sites and topologic characteristics of the carbon skeletons and include a perspective of the design and engineering of the nanocomposites for further enhancement of the electrocatalytic activity.