Ni-MoO2 cathodes for hydrogen evolution in alkaline solutions. Effect of the conditions of their electrodeposition

Abstract

The electrodeposition of Ni-MoO2 composite coatings is a specific process taking place under defined hydrodynamic conditions. In this work the influence of hydrodynamics, current density, and MoO2 concentration on the electrodeposition of Ni-MoO2 coatings from a suspension of MoO2 particles in a Watt’s type bath were investigated by com­parison of their polarization characteristics for the hydrogen evolution reaction (HER) in 1 M NaOH at room temperature. It was shown that electrolyte and air flow rates influence the process of coating electrodeposition at low concentrations of MoO2. With increases in MoO2 concentration the current density became the main parameter influencing the coatings’ properties. The best coating, with the lowest over-voltage for the HER, was obtained from the suspension containing 3 g dm-3 of MoO2 particles. The over-voltage of this coat­ing was 57 mV lower for the HER at j = –0.3 A cm-2 (the current density used in industrial applications) than that for the commercial De Nora’s Ni + RuO2 electrode.