Porous structure Ni/CuCo2O4 core–shell as a novel type of three-dimensional electrode with facile fabrication and binder-free toward enhanced methanol oxidation and supercapacitor performances

Abstract

In this present research, three dimensional nickel/copper cobaltite (3D-Ni/ CuCo2O4) core–shell nanocomposites have been successfully synthesized on 304 stainless steel as a substrate through the combination of electrodeposition and sol–gel methods followed by annealing treatment. The crystallographic configuration, chemical structure and surface morphology as-prepared materials are characterized systematically by different spectroscopy and microscopy techniques such as X-ray diffraction (XRD), fourier transformation spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) and field emission scanning electron microscope (FE-SEM). Bi-functional performance of samples are studied for supercapacitor and methanol fuel cell. According to achieved galvanostatic charge–discharge (GCD) results, 3D-Ni/ CuCo2O4 and CuCo2O4 electrodes maintains nearly 89.97 % and 56.55 % of the preliminary areal capacitance in high current density of 1.27 mA cm 2 , indicating high rate capability of 3D-Ni/ CuCo2O4 nanocomposite. Furthermore, it illustrates remarkable cycling stability in 1 M KOH solution during charge/discharge cycles in judgment with individual CuCo2O4. Enhanced electrochemical performances of nanocomposite are mainly due to the unique porous structure of 3D-Ni core and high electronic conductivity of CuCo2O4 as shell that synergistic effects of two component can eventually decrease the charge transfer resistance to improve the ion–electron transportations ability. More importantly, 3D-Ni/ CuCo2O4 exhibits the anodic peak current density of 18.67 mA cm 2 for methanol oxidation reaction at 0.55 V potential in 1 M KOH mixed with methanol which is greater than of 7.45 mA cm 2 CuCo2O4 when applied as catalyst of fuel cell. Unlike commonly accepted techniques, we reported a spin coater route for tight and stable deposition CuCo2O4 onto 3D-Ni surface without any adhesive.