Recent progress in Co-N-C single-atom catalysts for the electrochemical oxygen reduction reaction

Abstract

Cobalt-based single-atom catalyst supported on porous nitrogen-doped carbon (Co-N-C) has received extensive attention due to the excellent catalytic performance in the electrochemical oxygen reduction reaction (ORR). Co-N-C can catalyze ORR via different electron transfer pathways to generate water (H2O) or hydrogen peroxide (H2O2), respectively. Therefore, the rational design of the active sites and the optimization of the catalytic conditions are the key factors in the development of metal-air batteries, fuel cells and chemical industry. However, the key factors determining the selectivity of the ORR are still undefined. This review reports the recent progress on Co-N-C single-atom catalysts for the electrochemical ORR. The microenvironment of the single-atom sites and the test conditions for oxygen reduction reaction are summarized, with attention on the oxygen adsorption energy and reaction intermediate binding energy. Last, by highlighting the key factors for the selectivity determination, this work is expected to shed some light on the further development of Co-N-C for ORR.