Kinetics of the hydrogen evolution on nickel in alkaline solution: New insight from rotating disk electrode and impedance spectroscopy analysis

Abstract

Nickel catalysts were characterized for the hydrogen evolution reaction (HER) using rotating disk electrode (RDE) and electrochemical impedance spectroscopy (EIS). The theoretical Levich slope was calculated on the basis of the HER mechanism in alkaline solution. Kinetic and thermodynamic parameters of the reaction were obtained for fresh polished nickel electrode (Nif), and for nickel after a quick chronoamperometric aging procedure (Nipc). Koutecky-Levich analysis indicated that the rate determining step on Nif is the one-electron Volmer reaction, while for Nipc decreases from one to 0.68 and exhibits a strong temperature dependence. A loss of catalytic activity, corresponding to an increase of 0.3 V of the HER onset potential, was observed after aging. Furthermore, from the EIS-Tafel analysis we concluded that the H adsorption changes from a Langmuir type for Nif, to a Temkin type for Nipc.