关键词: NiCo₂O₄, 3D nanostructure, Electrochemical, Methanol oxidation, Current density

Abstract: Up to this date, researchers are still facing difficulties to expand the technology of direct methanol fuel cells (DMFCs) because of the high overpotential required to oxidize the methanol and its relatively poor performance due to CO poisoning of the leading-high cost anode catalyst. In line with this, we have successfully modified the morphological structure and composition of low cost cobalt based-metal oxides, MCo₂O₄ (M=Zn and Ni), with the simple and noble use of polyvinyl pyrrolidone (PVP) as growth modifier and surface stabilizer during the synthesis of nanoparticles in our previous reports, which shown high electrocatalytic activity and strong stability. Due to the good performance of our PVP modified MCo₂O₄ towards pseudocapacitor and oxygen evolution reaction applications, we decided to extend our research study to methanol oxidation reaction. Remarkably, PVP modified NiCo₂O₄ electrode directly grown on nickel foam substrate via a simple hydrothermal process exhibited better performance compared with PVP modified ZnCo₂O₄ and NiCo₂O₄ without PVP. It had obtained a remarkably low onset potential of 0.285 V and high current density of 280 mA cm^-2, and shown great stability and high poison tolerance during a continuous CV cycling and Chronoamperometry test, which attained high efficiency of 86.86% and 98.52%, respectively. These positive results of PVP modified NiCo₂O₄ electrode towards MOR might be attributed to its hierarchical 3D nanostructures with highly mesoporous surface and large surface area which may have provided numerous electroactive sites, and the exceptional corrosion stability of NiCo₂O₄ electrode in alkaline solution.

Key words: NiCo₂O₄, 3D nanostructure, Electrochemical, Methanol oxidation, Current density