Preparation and characterization of Pd-modified Raney-type NiZn coatings and their application for alkaline water electrolysis

Abstract

Cu/Ni/NiZn-Pd composite coatings were fabricated by combination of electrochemical and a simple chemical replacing methods to enhance hydrogen evolution activity of Raney-type electrodes and reduce the amount of Pd in the fabrication of cathodes for alkaline water electrolysis. The electrodes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) techniques. Cathodic polarization and electrochemical impedance spectroscopy (EIS) techniques were used to evaluate their electrochemical activity for hydrogen evolution reaction (HER) in 1 M KOH solution. It was reported that modification of the alkaline leached NiZn binary layers with low amounts of Pd enhances the HER activity of the electrodes. Their electrochemical activity strictly depends on the Pd content. The enhancement in the hydrogen evolution activity of the electrodes was attributed to the increase in their real surface area and/or a possible synergistic effect between Ni, Zn and Pd as well as well-known intrinsic catalytic activity of Pd. © 2016 Hydrogen Energy Publications LLC