Recent Developments in Carbon-supported Fe–N–C Catalysts for ORR in Fuel Cells: A Review

Abstract

The development of cost-effective and high-performance oxygen reduction reaction (ORR) catalysts is essential for the commercialization of fuel cells. Among the most promising PGM-free options, Fe–N–C catalysts stand out due to their tunable active site chemistry, favorable ORR activity, and economic viability. This review highlights the critical role of carbon-based supports in enhancing the performance of Fe–N–C catalysts across various fuel cell technologies. We examine the structure–property–performance relationships that govern the dispersion, stabilization, and electronic environment of Fe–Nₓ active sites, emphasizing how support properties such as porosity, conductivity, and surface chemistry influence catalytic activity and durability. Recent synthetic strategies, including one-pot and two-step pyrolysis and sacrificial support approaches, are summarized with a focus on their impact on catalyst performance. Particular attention is given to novel carbon materials, such as carbon nanotubes, graphene, and hierarchical porous carbons, evaluating their advantages and limitations as catalyst supports. Biochar is also featured as a sustainable, cost-effective, and tunable support with strong potential for scalable and environmentally friendly catalyst production. Finally, current challenges including carbon corrosion and active site degradation are discussed, alongside future research directions aimed at enabling practical implementation of carbon-supported Fe–N–C catalysts in real-world fuel cell applications.