A Stabilized Assisted Method for the Synthesis of Fe-N-C Catalysts for the Oxygen Reduction Reaction

Iron-nitrogen-carbon graphitic (Fe-N-C), a noble metal-free catalyst holds a lot of promise to substitute platinum (Pt) as an efficient catalyst in the oxygen reduction reaction (ORR). However, the synthesis process and the stabilization of single atoms that tend to aggregate, without jeopardizing the catalytic activity remain challenging. Here we demonstrate a stabilized assisted method for the preparation of Fe-N-C electrocatalyst by using graphitic carbon nitride (g-C3N4) nanosheet as a template. Fe ions are absorbed on the surface of g-C3N4 and imprisoned after the addition of pyrrole, preventing Fe migration that may result in nanoparticles. During the pyrolysis, Fe atoms coordinated with N provided by g-C3N4 and pyrrole on graphitic carbon to form Fe-N-C with a metal loading of 5.4 wt%. Moreover, FeNx species were introduced in the graphitic carbon, where the coexistence of micro and mesopores were favorable to offer a larger density of active sites compared to Fe/NP without pyrrole. Fe-N-C demonstrated a good electrocatalytic performance with a half-wave potential (E (1/2)) of 0.82 V (vs reversible hydrogen electrode (RHE)) higher than Fe/NP (0.76 V) and close to Pt/C, with a superior long stability of 85% in alkaline media after 40000 s.