Spinel CoFe2O4 supported by three dimensional graphene as high-performance bi-functional electrocatalysts for oxygen reduction and evolution reaction

Spinel CoFe2O4 supported on three dimensional graphene (3DG) is prepared by hydrothermal reaction, which is denoted as CoFe2O4/3DG. The 3DG is prepared by the templated method, where coal tar pitch (CTP) and MgO are used as the carbon source and the template, respectively. The microstructure and composition of the resultant have been investigated by X-ray diffraction as well as X-ray photoelectron spectroscopy indicating the formation of spinel CoFe2O4 and composite of CoFe2O4/3DG. The multilayer structure of 3DG and CoFe2O4/3DG is also examined by the Raman spectra. Electrochemically, CoFe2O4/3DG shows high-performance half-wave potential is 0.80 V vs. RHE in O-2-saturated 0.1 M KOH, which is compared to 20 wt% Pt/C. When evaluated for OER activity, CoFe2O4/3DG obtains a low overpotential 1.63 V vs. RHE (at j = 10 mA cm(-2)), which is 180 mV better than 20 wt% Pt/C. Moreover, it possesses excellent durability superior to 20 wt% Pt/C. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.