Recent Progress in the Identification of Active Sites in Pyrolyzed Fe−N/C Catalysts and Insights into Their Role in Oxygen Reduction Reaction

Iron and nitrogen codoped carbon (Fe-N/C) catalysts have emerged as one of the most promising replacements for stateof-the-art platinum-based electrocatalysts for oxygen reduction reaction (ORR) in polymer electrolyte fuel cells.During the last decade, significant progress has been achieved in Fe-N/C catalysts in terms of ORR activity improvement and active site identification.In this review, we focus on recent efforts towards advancing our understanding of the structure of active sites in Fe-N/C catalysts.We summarize the spectroscopic and electrochemical methods that are used to analyze active site structure in Fe-N/C catalysts, and the relationship between active site structure and ORR activity in these catalysts.We provide an overview of recently reported synthetic strategies that can generate active sites in Fe-N/C catalysts preferentially.We then discuss newly suggested active site…