Reduced Graphene Oxide Supported NiCo2O4 Nano-Rods: An Efficient, Stable and Cost-Effective Electrocatalyst for Methanol Oxidation Reaction

The development of inexpensive, highly active and non-noble catalysts for the methanol oxidation reaction is extremely desirable for the practical use of direct-methanol fuel cells. Here, we have developed a template-free hydrothermal synthesis followed by calcination to produce highly active hybrid material of reduced graphene oxide (rGO) supported NiCo2O4 (NiCo2O4/rGO) nano-rods as a non-expensive electro-catalyst for methanol oxidation. The electrochemical performance of the prepared NiCo2O4/rGO spinel catalyst was investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) techniques. Impressively, the NiCo2O4/rGO showed greater electrocatalytic activity (78 mA/cm(2)) and stability during methanol oxidation in comparison to that of the commercial Pt/C catalyst, which was 3.11 folds higher than the commercial Pt/C (25.08 mA/cm(2)). The NiCo2O4/rGO electrode also maintained its remarkable catalytic stability even after consecutive 500 cycles, which was similar to 50 times higher than that of the commercial Pt/C. The overall electroactivity of NiCo2O4/rGO was remarkably enhanced by the synergistic effect between NiCo2O4 and rGO. This may be due to the formation of mixed-valence cations of Ni2+ and Co3+ from the octahedral sites and high electron-transfer conductivity of rGO as well.