Ni-Co electrodes prepared by electroless-plating deposition. A study of their electrocatalytic activity for the hydrogen and oxygen evolution reactions

Nickel-cobalt based electrodes with different Ni-Co ratios have been prepared by electroless-plating deposition from NiSO4 and CoSO4 solutions. The performance of the electrodes for the HER and OER reactions has been examined by linear sweep voltammetry. The electrode containing only nickel (Ni-ELP) displays the lowest overpotential for the HER. On the other hand, the Ni-Co electrode with Co concentrations of 30 at% (Ni70Co30-ELP) exhibits the lowest overpotential for OER. Durability tests have been carried out with these two electrodes. The potential of electrolytic cell at 0.3 A cm−2, using Ni-ELP for the HER and Ni70Co30-ELP for the OER, was of 2.2 V. Characterization of the used electrodes by SEM/EDS reveals that the structure of the electrodes remains stable after H2O alkaline electrolysis for 70 h. The results presented in this work show that the electroless-plating method is a successful way to prepare stable nickel electrodes for alkaline water electrolysis.