Effects of Particle Sizes on Alkaline Water Electrolytic Catalytic Properties of Laser Sprayed Nickel Coatings

Laser spraying technology is a new type of thermal spraying technology， which is based on the principle of using laser as a heat source to heat the powder so that the particles reach a molten or semi-molten state and form a coating on the surface of the substrate.In this work， the nickel coatings were fabricated on the surface of nickel mesh through laser spraying.The surface morphology of the coatings was characterized by scanning electron microscopy (SEM).The catalytic activity of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of electrodes was characterized by electrochemical methods， and the effect of nickel particle size on the electrolytic catalytic performance of coatings was studied.The results showed that the particle size affected the degree of melting of the particles when passing through the laser.The number of particles deposited on the surface of the prepared electrodes increased as the particle size decreased， and pore structure particles were found on the electrode surface， while the HER and OER overpotentials of the electrodes decreased， the double-layer capacitance value increased， and the impedance decreased， indicating that the HER and OER activities of the prepared electrodes were enhanced.The electrode prepared with an average particle size of 45 μm powder showed the best catalytic activity in HER and OER， with overpotentials of 416 mV and 371 mV， respectively， at a current density of 10 mA/cm2.This study provided a new method for the efficient and low-cost green preparation of catalytic electrodes for hydrogen production by alkaline water electrolysis.