The dynamics of the nickel foam formation and its effect on the catalytic properties toward hydrogen evolution reaction

Abstract

Porous nickel deposits were obtained by electrodeposition via dynamic hydrogen bubble template in a galvanostatic mode at a current density of 0.3, 0.6, 0.9 and 1.2 A·cm−2. Change of nickel foam morphology (dendrite particles, pore number and their sizes) with the applied current density was analyzed. It was found that at low hydrogen evolution rate, a gradual formation of a porous structure occurs, while at high ones, the formation of the template structure ends in the first minutes of electrolysis. It is shown that the log-normal distribution can be used to describe the formation of a hydrogen template as a system of nickel foam macropores. The catalytic activity of nickel foams toward hydrogen evolution was analyzed in an alkali solution. The Tafel slope for the obtained foams is in the range of 126-107 mV·dec−1. Nickel foams obtained at 1.2 A·cm−2 are the best candidates for hydrogen evolution electrodes due to their stable structure, providing maximum access of reacting particles to the inner surface of the electrode.