Reduced graphene oxide-NiCo2O4 nanoflowers as efficient electrocatalysts for the oxygen reduction reaction

Two-dimensional materials have already become the focus of many researches due to their innovation potential in various fields related to their special structure. Particularly, more and more two-dimensional electrocatalysts are being developed for the oxygen reduction reaction (ORR). In this work, novel two-dimensional NiCo2O4 nanoflowers/reduced graphene oxide (NCONFs/rGO) nanocomposite ORR catalysts have been successfully synthetized via a two-steps method. The micromorphology and microstructure of the obtained samples were analyzed via XRD, SEM, TEM and Raman spectroscopy. The different characterizations showed a typical petal-like structure of NiCo2O4 and a good coupling between NCONFs and rGO. Electrochemical measurements demonstrated both superior NCONFs/rGO ORR activity (0.92 V of onset potential, vs. RHE) and an excellent catalytic stability (6.4% decrease in current during a 10,000 s test). Such outstanding performances have never been reported before for ORR catalysts and originate from the two-dimensional microstructure of materials combined with the supporting rGO layer. (C) 2017 Published by Elsevier B.V.