Synthesis of Fe–N–C Single-Atom Catalysts with a Facile Salt-Templated Strategy for Efficient and Stable Oxygen Reduction Reaction

The active Fe–N–C single-atom catalysts (Fe–N–C SACs) are considered the best alternatives to platinum-containing electrocatalysts for the application of metal–air batteries and fuel cells. However, several issues regarding facile preparation and stability still need to be resolved. This work proposes a facile molten NaCl-templated strategy to synthesize Fe–N–C SACs with Fe2O3 as the Fe source. The introduction of molten NaCl during pyrolysis generates abundant micropores, whose volume reaches a 3-fold enhancement over the NaCl-free sample. The specific surface area increases to 1617.8 m2 g–1, providing more accessible sites to host Fe atoms and improving mass transfer efficiency. The optimal Fe–N–C SACs demonstrate outstanding oxygen reduction reaction (ORR) activity with an exceedingly high half-wave potential of 0.91 V in alkaline media. They also overcome the dependence of activity and stability on the pH of the electrolyte. This work proposes an innovative approach to enable the systematic development of high-performance ORR catalysts, demonstrating the feasibility of employing salt templating for fabricating atomically dispersed catalysts.