Synthesis of mesoporous NiCo2O4 fibers and their electrocatalytic activity on direct oxidation of ethanol in alkaline media

• Mesoporous NiCo2O4 fibers were synthesized by a simple template-free method.
• The NiCo2O4 fibers displayed fibrous morphology with well-distributed mesopores.
• The mesoporous NiCo2O4 fibers were used as anodes for direct ethanol fuel cells (DEFCs).
• The NiCo2O4 fibers exhibited excellent electrocatalytic activity for ethanol oxidation.
• A notable reduction was found in the onset potential on NiCo2O4 electrodes.

Well-dispersed mesoporous NiCo2O4 fibers as anode catalysts for the electrooxidation of ethanol were synthesized by an easy-controlled template-free method. Their structure and morphology were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption/desorption analysis. The electrochemical oxidation of ethanol on mesoporous NiCo2O4 fibers modified glassy carbon electrode (NiCo2O4/GCE) in alkaline solutions was systematically evaluated by cyclic voltammetry (CV), double-step chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The NiCo2O4 materials showed typical intertwined porous nanofibrous structures with specific surface area of 54.469 m2 g−1 and average pore size of 13.5 nm. The NiCo2O4/GCE exhibited significantly high electrocatalytic activity with higher current density and lower onset potential compared to those of Co3O4 and NiO in CV measurement. The linear relationship between the ethanol concentration and the square root of scan rate indicated that diffusion of ethanol is a rate-determining step in its oxidation on mesoporous NiCO2O4 fibers. The electrochemical mechanism of ethanol oxidation on NiCo2O4/GCE was also proposed.