The Mechanism of Hydrogen Evolution Reaction on a Modified Raney Nickel Composite‐Coated Electrode by AC Impedance

Abstract

The hydrogen evolution reaction (HER) on a modified Raney nickel electrode, consisting of Ni-Al-Cu-Cr alloy, was investigated with ac impedance measurements and by dc polarization current behavior in 5.36M KOH solution at 70C. Comparative measurements also were carried out on commercial Raney nickel (Ni-Al). The rate constants of the forward and backward reactions of Volmer, Heyrovsky, and Tafel steps were estimated by a nonlinear fitting method. The modified Raney nickel composite-coated electrode provides a lower overpotential for the HER than the commercial Raney nickel-coated electrode. The main pathway for the HER is Volmer-Tafel with Volmer as the rate determining step.