Cost-effective electrocatalyst as alternative to Pt for the oxygen reduction reaction (ORR) is one of the key requirements for viable fuel cells. Hybrids of metal oxides and nitrogen (N)- doped carbon (NC) are promising candidates, while effective synthesizing methods are highly expected. We report an efficient hybridization of Fe₃O₄ and NC by simply annealing FeOOH nanorods together with urea at a relatively low temperature (500 C). The urea is ingeniously chosen to act as the reductant to convert FeOOH into Fe₃O₄ and as the source to form NC on Fe₃O₄ nanorods at the same time; while Fe species in FeOOH/Fe₃O₄ catalyze the reaction from urea to NC. Such synergetic effects are vital for the hybrid formation. The as-synthesized hybrid exhibits attractive ORR activity, with an onset potential of ~0.915 V (vs. RHE) and a half-wave potential of 0.806 V (vs. RHE) in alkaline media, which are superior to that reported so far for the Fe₃O₄-based materials and N-doped carbons.

        https://doi.org/10.1016/j.ijhydene.2016.07.158