Ni/Re-Co as electrocatalytic material for hydrogen evolution reaction in alkaline solution

Abstract

The electrochemical behaviour of two modified electrodes, Ni/Re 87-Co7 and Ni/Re57-Co37 (electrodeposited Ni, covered with a thin layer of electrodeposited Re-Co alloy), was studied with respect to the hydrogen evolution reaction (HER) in a 6 M KOH solution. The data are compared with those of the pure Ni electrode. Cyclic voltammetry, polarization measurements at various current densities, and the electrochemical permeation technique of Devanathan-Stachurski were used. Kinetics parameters of HER were determined on the basis of the Tafel plots. The diffusion coefficient of permeating hydrogen and the hydrogen concentration in the electrode subsurface were calculated on the basis of permeation transients. Both modified electrodes show significantly higher values of hydrogen evolution rate and exchanged current density than those of the pure Ni electrode. The values of HER overpotential on both modified electrodes are similar, and most important is that they are much lower than the HER overpotential value on the pure Ni electrode. The hydrogen permeation data are in accordance with the voltammetric measurements. Ni electrode, modified by alloy with a lower Re content (Ni/Re57-Co37), shows best electrocatalytic properties with regards to HER. © 2011 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.