Microwave-assisted fast synthesis of hierarchical NiCo₂O₄ nanoflower-like supported Ni(OH)₂ nanoparticles with an enhanced electrocatalytic activity towards methanol oxidation

NiCo₂O₄ nanoflowers were synthesized through a microwave-assisted hydrothermal method and used as a type support for Ni(OH)₂ nanoparticles. In the three-dimensional NiCo₂O₄ nanoflowers, two-dimensional ultrathin nanosheets supported the Ni(OH)₂ nanoparticles by homogeneous precipitation. The materials were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The electrochemical oxidation of methanol was probed through the NiCo₂O₄/Ni(OH)₂ modification on a glassy carbon electrode in an alkaline medium by employing cyclic voltammetry (CV) and chronoamperometry (CA). The current density of the NiCo₂O₄/Ni(OH)₂ electrode in 1 M KOH with 0.5 M methanol ascends to 92.3 A g^-1 and restores to 94.6% of the primitive value through the replacement with a new solution after a long-term CV cycling (500 cycles). Therefore, the compounds further corroborate their excellent electrocatalytic activity and superb perennial stability for methanol oxidation. This study demonstrates that NiCo₂O₄/Ni(OH)₂ is a peculiar material with an outstanding performance in direct methanol fuel cells.