Graphene layers‐wrapped Fe/Fe5C2 nanoparticles supported on n‐doped graphene nanosheets for highly efficient oxygen reduction

Abstract

Synthesis of highly efficient nonprecious metal electrocatalysts for the oxygen reduction reaction (ORR) superior to platinum (Pt) is still a big challenge. Herein, a new highly active ORR electrocatalyst is reported based on graphene layers-wrapped Fe/Fe5C2 nanoparticles supported on N-doped graphene nanosheets (GL-Fe/Fe5C2/NG) through simply annealing a mixture of bulk graphitic carbon nitride (g-C3N4) and ferrocene. An interesting exfoliation–denitrogen mechanism underlying the conversion of bulk g-C3N4 into N-doped graphene nanosheets is revealed. Owing to the high graphitic degree, optimum N-doping level and sufficient active sites from the graphene layers-wrapped Fe/Fe5C2 nanoparticles, the as-prepared GL-Fe/Fe5C2/NG electrocatalyst obtained at 800 °C exhibits outstanding ORR activity with a 20 mV more positive half-wave potential than the commercial Pt/C catalyst in 0.1 m KOH solution and a comparable onset potential of 0.98 V. This makes GL-Fe/Fe5C2/NG an outstanding electrocatalyst for ORR in alkaline solution.