Electrochimica Acta, Vol.56, No.3, 1308-1315, 2011
Impedance study of hydrogen evolution on Ni/Zn and Ni-Co/Zn stainless steel based electrodeposits
A study on the electrocatalytic performance of Ni/Zn and Ni-Co/Zn alloys for hydrogen evolution reaction (HER) in alkaline media (30 wt.% KOH solution) 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 layer. For the developed electrodes, the surface roughness factor, R-f, was evaluated by electrochemical impedance spectroscopy (EIS). The HER on these electrodes was evaluated by means of steady-state polarization curves and EIS. The obtained electrodes were characterized by large R-f for HER, and very low overpotentials at the current density of 250 mA cm(-2), eta(250) similar to 0.138 V at 30 angstrom C. The high electrode activity was mainly attributed to the high surface area of the developed electrodes. (C) 2010 Elsevier Ltd. All rights reserved.
Keywords:Electrochemical impedance spectroscopy;Hydrogen evolution reaction;Surface roughness factor;Nickel-cobalt/zinc alloys