Composition, morphology, structural aspects and electrochemical properties of Ni–Co alloy coatings

Nickel–cobalt alloys having settled composition can be produced by electrolysis after optimising process operative conditions. In this work nickel–cobalt coatings on 1050 Al net, obtained by electrodeposition under galvanostatic conditions, were investigated. Ni–Co coatings were electrowon, from an acidic sulphate bath containing 40 g/L Ni and Co in the range 0.1–16 g/L, at 60 °C temperature and 300 A/m2 average current density. The experimental results highlight a linear correlation between bath and deposit Co/Ni ratio, with slope change for Co concentration in the electrolyte higher than 3 g/L. Morphology, structure and electrochemical properties are strictly correlated among themselves and with the composition of the coating.

► Ni–Co coatings with settled composition were produced by electrolysis.
► Linear correlation between bath and deposit Co/Ni ratio is shown.
► Morphology, structure, electrochemical properties and coating composition are strictly correlated.
► Ni–Co alloys with 40–65% Co are the best cathodic material for HER in alkaline media.
► Cubic structure and finer globular morphology give the best catalytic properties.