Nickel particles with increased catalytic activity towards hydrogen evolution reaction

Nickel particles are synthesized by a modified polyol method using 1 at. % of Pd as nucleation agent (Ni99Pd1) followed by an electrochemical sinusoidal wave treatment in 0.1 M Na2SO4 + 30 mM ascorbic acid. This treatment proved to significantly enhance the catalytic activity of Ni towards the hydrogen evolution reaction (her). After treatment, the current density of her increases almost four times and is accompanied by the onset potential shift to more positive values. From SEM, no visible changes in Ni particle size and shape were observed after treatment. XPS analysis of the surface of as-prepared Ni particles reveals that it contains Ni0, NiO, NiOOH and Ni(OH)2, whereas after treatment Ni atoms exist mainly in the metallic form and as NiOOH. The increase in the activity of Ni particles after the treatment might be due to the higher amount of Ni0 at the surface.