Recent advances in active sites identification and regulation of M-N/C electro-catalysts towards ORR

Abstract

Transition metal and nitrogen co-doped carbon (M-N/C) catalysts are recognized as the most prospective alternatives for platinum-based electro-catalysts towards oxygen reduction reaction (ORR) in polymer electrolyte fuel cells. Recently, significant progress has been achieved in the identification and regulation of active sites of this kind of catalysts. In this mini review, we summarize the techniques and strategies to identify active sites in M-N/C catalysts, the main debates on active sites types, the measurement method for active site density, the reactivity descriptors for M-N/C catalysts, and directions to the design of ORR M-N/C catalysts.