Comparison of Electrocatalytic Hydrogen Evolution Properties of Ni-Co and Ni-Co-WC Porous Electrodes

Abstract

The porous electrode of (Ni-Co)0 and (Ni-Co)30 for electrocatalytic hydrogen evolution were prepared by electroplating on a sponge Co based alloy Co69.9Ni30.1 matrix. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were used to characterize the surface images and the crystal structure of the electrodes, respectively. Polarization curves, electrochemical reaction AC impedance spectroscopy (EIS), cyclic voltammetry (CV) curves and amperometric i-t curves were used to compare their electrocatalysis for hydrogen evolution reaction (HER) in the dilute sulphuric acid solution with concentration of 0.5M. The surface of the composite coating (Ni-Co)30 is densely packed with coarse particles like peanut shell, which are agglomerated by a large number of tiny particles. The specific surface ratio of (Ni-Co)30 is higher than that of the (Ni-Co)0 coating. The structure of (Ni-Co)30 is a biphasic structure with WC dispersed in the Ni-Co solid solution. The results show that the HER overpotential, the electrochemical impedance and the apparent activating energy of the reaction of hydrogen evolution for the porous (Ni-Co)30 are lower than those of the porous (Ni-Co)0. When the temperature is 25-50℃, the exchange current density of HER for (Ni-Co)30 is 8.92-15.78 times greater than that of the porous (Ni-Co)0. The HER overpotential of (Ni-Co)30 at a current density of 10mA/cm 2 is 0.118V lower than that of (Ni-Co)0. The activation energy of the HER of the (Ni-Co)30 at the overpotential of 0.2V is 20kJ/mol smaller than that of the (Ni-Co)0. The (Ni-Co)30 has excellent oxidation resistance and super HER stability, as does the (Ni-Co)0. The electrocatalytic HER performance of the composite electrode (Ni-Co)30 is better than that of the (Ni-Co)0.