Modeling of the porous nickel deposits formation and assessing the effect of their thickness on the catalytic properties toward the hydrogen evolution reaction

• Published in: International journal of hydrogen energy 2021-05, Vol.46 (32), p.16857-16867
• Main Authors: Trofimova, Tina-Tini S., Ostanina, Tatjana N., Nikitin, Vjacheslav S., Rudoi, Valentin M., Ostanin, Nickolaj I., Trofimov, Aleksej A.
• Format: Article
• Language: English
• Subjects: Electrodeposition; HER; Loose deposits; Nickel foam; Porosity
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2021.02.093

Hydrogen used as an energy carrier can be obtained by water electrolysis. To improve the energy efficiency of this process porous nickel catalysts are often used. The paper investigates the electrodeposition regularities and the porous nickel deposits morphology and the properties of nickel foams toward the hydrogen evolution reaction. During electrodeposition at high current density, nickel deposits with macro- and micropores are formed. The dependence between the fraction of macropores on the deposit surface and the electrolysis time is described by the empirical equation. Total porosity of loose nickel deposits is much higher than the porosity of foams. However, the surface macropores fraction of deposits studied is approximately the same, while the microporosity of loose deposits is significantly higher. The values of nickel deposits total porosity calculated by the model agree with the values obtained by experimental data. The highest density of macropores on the surface is observed for the foam thickness of 100 μm. These data correlate with the results of polarization measurements. When the foam thickness increases up to 100 μm, hydrogen evolution overvoltage in the alkali solution decreases and the efficiency of nickel foam as a cathode material increases. [Display omitted] •A change in the nickel deposits porosity during electrodeposition was determined.•Empirical equation for calculating the macropores fraction is proposed.•A change in deposits microporosity was calculated using model representations.