Recent Advances in Tailoring Active Site Microenvironments of Fe–N–C Catalysts for Oxygen Reduction

The oxygen reduction reaction (ORR) is a key process in energy conversion devices such as fuel cells and metal‐air batteries, yet its slow kinetics significantly limit overall performance. Current ORR practicality largely relies on the utilization of platinum‐group metals, facing challenges in scarcity, high cost, and poisoning tolerance. Iron–nitrogen–carbon (Fe–N–C) catalysts have emerged as promising platinum‐group‐metal‐free alternatives due to their low cost, tunable structure, and strong ORR activity in pH‐universal environments. These atomically dispersed Fe–N x sites have wide tunability in electronic state and local coordination, exhibiting great potential in activity/stability enhancement and selectivity switching. However, challenges such as Fe leaching, carbon corrosion, and the formation of inactive phases limit their durability. This review outlines the main factors influencing the activity and stability of Fe–N–C catalysts and summarizes recent strategies for improvement, including dual‐metal doping, porosity engineering, advanced synthesis methods, and protective encapsulation. These insights provide a pathway for designing next‐generation ORR catalysts for sustainable energy applications.