EIS Characterization of Ni/Zn and Ni-Co/Zn Stainless Steel Based Electrodeposits for the Hydrogen Evolution Reaction

A study on the electrocatalytic performance of Ni/Zn and Ni-Co/Zn alloys for hydrogen evolution reaction (HER) in alkaline media has been carried out. After preparing, by electrodeposition on stainless steel supports, the alloys were leached of to remove part of the zinc and generate a porous surface. For the developed electrodes, the surface roughness factor, Rf, one of the most important problems in electrocatalysis, was evaluated by Electrochemical Impedance Spectroscopy (EIS). The HER on these electrodes was evaluated by applying steady-state polarization curves and EIS. The obtained electrodes were characterized by large roughness factors for HER, Rf ~ 5000 and very low overpotentials at the current density of 250 mA cm-2, η250 ~ 0.32 mV at 30 ºC. The high electrode activity was mainly attributed to the high surface area of the developed electrodes.