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

Abstract

Abstract 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 NiCo 2 O 4 (NiCo 2 O 4 /rGO) nano‐rods as a non‐expensive electro‐catalyst for methanol oxidation. The electrochemical performance of the prepared NiCo 2 O 4 /rGO spinel catalyst was investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) techniques. Impressively, the NiCo 2 O 4 /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 NiCo 2 O 4 /rGO electrode also maintained its remarkable catalytic stability even after consecutive 500 cycles, which was ∼50 times higher than that of the commercial Pt/C. The overall electroactivity of NiCo 2 O 4 /rGO was remarkably enhanced by the synergistic effect between NiCo 2 O 4 and rGO. This may be due to the formation of mixed‐valence cations of Ni 2+ and Co 3+ from the octahedral sites and high electron‐transfer conductivity of rGO as well.