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

Mixed Ni Co-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 Ni Co-oxide cathodes, and also on the pure metal Ni electrode (control). The Ni 0.2 Co 0.8 -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 Ni 0.2 Co 0.8 -oxide electrode showed a significantly higher electrocatalytic stability (fouling/deactivation tolerance) in comparison to metallic Ni. • Ni Co-oxide cathodes produced hydrogen in acidic and alkaline media. • The cathodes had a semi-crystalline structure and a high surface roughness. • Ni 0.2 Co 0.8 -oxide yielded the highest apparent electrocatalytic activity. • Nickel electrode showed the highest intrinsic electrocatalytic activity. • Ni Co-oxides were found to be more fouling/deactivation-resistant than Ni.