Ce-Doped Fe–N–C/Fe₃C Nanosheets as an Efficient Oxygen Electrocatalyst under Alkaline and Acidic Media

Abstract

Reasonable design of an economical and efficient versatile oxygen electrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is urgently needed in metal-air batteries and fuel cells. Herein, a Ce-doped Fe-NC/ Fe 3 C (Ce/Fe-NC/Fe 3 C-P) porous nanosheet catalyst was prepared from the pyrolysis of a two-dimensional ZIF assisted with NaCl molten salt. Under alkaline media, the ORR half-wave potential (E 1/2 ) is 0.87 V, and the OER overpotential is 389 mV. The Zn-air batteries (ZABs) assembled with the Ce/Fe-NC/Fe 3 C-P catalyst demonstrate a maximum power density (P M ) of 184 mW cm −2 . Under acidic media, the E 1/2 of the ORR is 0.78 V, and the P M is 347 mW cm −2 in the proton exchange membrane fuel cell (PEMFC) cathode. The enhanced catalytic activity and stability benefit from the abundant catalytic active sites (Fe 3 C, Fe−N X , Ce− N) by Fe and Ce doping, hierarchical porous structure, and relatively higher graphitization originating from the molten NaCl assisting pyrolysis.