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

Abstract Well-dispersed mesoporous NiCo 2 O 4 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 N 2 adsorption/desorption analysis. The electrochemical oxidation of ethanol on mesoporous NiCo 2 O 4 fibers modified glassy carbon electrode (NiCo 2 O 4 /GCE) in alkaline solutions was systematically evaluated by cyclic voltammetry (CV), double-step chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The NiCo 2 O 4 materials showed typical intertwined porous nanofibrous structures with specific surface area of 54.469 m 2  g −1 and average pore size of 13.5 nm. The NiCo 2 O 4 /GCE exhibited significantly high electrocatalytic activity with higher current density and lower onset potential compared to those of Co 3 O 4 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 NiCO 2 O 4 fibers. The electrochemical mechanism of ethanol oxidation on NiCo 2 O 4 /GCE was also proposed.