Characterization of thermally diffused thermal spray Raney Ni coatings for electrolysers applications

Alkaline water electrolysis (AWE) is one of the most mature technologies for hydrogen production, with a large market outreach. Recently, research has been conducted on efficient and low-cost electrode materials with the aim of increasing the efficiency of AWE and reducing its costs. Among these electrode materials, Ni-Al alloys (Raney Ni) have been extensively studied for application in AWE. Due to their highly porous microstructure, obtained by leaching Al from the Ni-Al alloy, they show promising electrochemical catalytic properties. Thus, they can be potential alternatives to Pt for the hydrogen evolution reaction (HER).

In this study, a two steps process has been used to coat Ni substrates. During the first step, Raney Ni coatings have been deposited by Atmospheric Plasma Spraying on Ni substrates. During the second step, diffusion heat treatments have been carried out at temperatures below aluminium melting point. All samples were characterized by X-Ray diffraction (XRD) and scanning electron microscopy (SEM/EDX) in order to investigate the microstructure and the chemical composition of the coatings in the as-sprayed condition, after diffusion treatments, and after chemical leaching. Galvanodynamic tests were carried out to characterize the electrochemical performance of the obtained Raney-type coating electrodes.