One‐Pot Synthesis of a Highly Active 3‐Dimensional Fe−Nx−CNTs/rGO Composite Catalyst for Oxygen Reduction

Abstract

AbstractA facile one‐pot method to synthesize a Fe−Nx−CNTs/rGO catalyst by using melamine and FeCl2⋅4H2O as low‐cost precursors is reported.The 3‐dimensional porous structure and the dispersion of precursor were completed at the same time. Suitable precursor and concentration selection not only solved the aggregation of graphene but also improved its effective iron content and activity. The obtained catalysts exhibited oxygen reduction activitycomparable to commercial Pt/C with a half‐wave potential (the potential when current density reaches the half of the diffusion‐limited current density) at 0.875 V(vs. RHE) in alkaline media. In addition, it also showed a better stability than Pt/C with a lower decay of E1/2 (10 mV) after 2000 cycles. From the systematic physical characterizations including aberration‐corrected scanning transmission electron microscopy, 57Fe Mössbauer spectroscopy and X‐ray absorption spectroscopy, it was discovered that a unique structure with the coexistence of nitrogen‐coordinated single iron atoms and Fe/Fe2C nanocrystals had been formed.