Wire-arc sprayed nickel based coating for hydrogen evolution reaction in alkaline solutions

Nickel based coatings of various Ni/Al ratios were prepared by the wire-are spray technique on mild steel substrate. High porosity Ni based electrodes were obtained by leaching out the aluminum in concentrated KOH at 70 degrees C. These electrodes were studied under hydrogen evolution reaction in 1 M NaOH at 25 degrees C. Good mechanical electrode stability and very low overvoltage values, i.e., down to 179 mV at 0.25 A/cm(2), were observed. These low overvoltages have been related to the porosity of the material by AC impedance measurements. This spray technique exhibits several advantages for processing large scale electrode materials at low cost. (C) 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.