Active sites identification and engineering of M-N-C electrocatalysts toward oxygen reduction reaction

Zinc-air batteries (ZABs) and Proton exchange membrane fuel cells (PEMFCs) have attracted wide attention because of their high energy density. However, the oxygen reduction reaction (ORR) occurred at the cathode is 6 orders of magnitude lower than the oxidation reaction occurred at the anode. In recent years, atomically dispersed metal-nitrogen carbon (M-N-C) catalyst has been widely considered as one of the most promising catalysts to replace platinum-based catalysts. However, the performance of M-N-C catalyst is much lower than that of the most advanced Pt catalysts. The key to improving the catalytic activity of M-N-C ORR catalysts is to increase the intrinsic activity of the catalyst active sites. In this paper, the active sites of atomically dispersed M-N-C ORR catalysts are introduced, and the strategies of enhancing the intrinsic activity of the active sites including heteroatom doping, construction of dual atoms sites and creation rich defects in carbon materials are systematically summarized. Finally, the opportunities and challenges of further development of atomically dispersed M-N-C catalysts are proposed. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.