“…Hydrogen-fed proton exchange membrane fuel cells (PEMFCs) hold great potential in mitigating environmental and energy crises. − However, their commercialization on a large scale is primarily hampered by the presence of costly platinum group metal (PGM) catalysts for their oxygen reduction reaction (ORR) on the cathode side. , In this regard, it is imperative to fabricate economical and earth-abundant PGM-free alternatives. Among them, transition metal and nitrogen-doped carbonaceous materials, for example, Fe/N/Carbon, are the most efficient materials. − With a decade of effort, substantial advancement has been introduced in Fe/N/Carbon catalysts which still exhibit lesser activity than the commercially reported Pt/Carbon catalysts. − At 8-fold higher catalyst loading (4 vs 0.5 mg cm –2 using 20 wt % Pt/Carbon catalysts at 0.1 mg Pt cm –2 loadings), the activation polarization performance of the Fe/N/Carbon cathode can be comparable with that of the low-loading Pt/C cathode. , However, the thick layer of the catalyst (100 μm in Fe/N/Carbon vs 10 μm in Pt/Carbon) results in severe mass-transfer problems and thus significant polarization loss at large current densities. − To solve this issue, the Fe/N/Carbon catalytic activity should be further enhanced.…”