Nickel-cobalt-oxide cathodes for hydrogen production by water electrolysis in acidic and alkaline media

Mixed NiCo-oxide cathodes of various compositions were fabricated by a thermal-decomposition method and used as electrocatalysts for hydrogen production by water electrolysis in acidic and alkaline media. The oxide electrodes were found to be of a semi-crystalline structure, yielding the surface morphology characterized by a surface roughness factor going up to 25. Linear potentiodynamic and potentiostatic electrochemical measurements revealed that the Volmer reaction step controlled the kinetics of the hydrogen evolution on all the NiCo-oxide cathodes, and also on the pure metal Ni electrode (control). The Ni0.2Co0.8-oxide was identified as the best electrode material candidate among the investigated metal oxides, which was linked to the surface-area effect. However, its intrinsic activity was found to be lower than that of pure metallic Ni. Nevertheless, the Ni0.2Co0.8-oxide electrode showed a significantly higher electrocatalytic stability (fouling/deactivation tolerance) in comparison to metallic Ni.