Three-dimensional electrode coatings for hydrogen production manufactured by combined atmospheric and suspension plasma spray

Nickel-based electrode coatings for hydrogen production by alkaline water electrolysis were prepared using atmospheric plasma spraying (APS) and suspension plasma spraying (SPS) methods. To enhance the active surface area of the electrodes and obtain various levels of surface roughness, three-dimensional fin arrays were fabricated by masking the substrates with mesh screens during APS deposition. Subsequently, SPS top coatings were deposited on the fin-structured electrodes. The electrodes were then characterized by studying their surface microstructure, topography, roughness and electrochemical performance. The highest electrocatalytic activity with the exchange current density of 1.8 × 10− 3 A/cm2 and overpotential (η250) of − 339 ± 15 mV was obtained for the electrode coated by the combined APS-SPS method using the mesh screen with the smaller opening size. The high activity of this electrode is mainly attributed to the unique surface structure formed by deposition of particles through the fine mesh screen and impacting at different angles on the fin geometry.