Enhanced oxygen evolution at hydrous nickel oxide electrodes via electrochemical ageing in alkaline solution

• Oxygen evolution reaction overpotential decreases by ca. 60 mV due to ageing.
• Oxygen evolution reaction rate of nickel oxide film increased by a factor of 10.
• Electrochemical ageing increases the turnover frequency from 0.05 s− 1 to 1.16 s− 1.

The effect of electrochemically ageing hydrous nickel oxide films via slow repetitive potential multi-cycling across the main nickel (II/III) redox peak was investigated in an aqueous base environment using cyclic voltammetry and steady state polarisation curves in the oxygen evolution reaction (OER) region. Similarities between hydrous nickel oxide films and electroprecipitated ‘battery type’ nickel oxide were shown due to their similar change in redox and oxygen evolving properties as a result of film ageing. This ageing method was found to significantly enhance the OER performance of the hydrous nickel oxide electrode with the OER overpotential decreasing by 60 ± 2 mV and experiencing a 10 fold increase in OER rate for a fixed overpotential over that of an un-aged electrode. The OER turnover frequency for an aged electrode was found to be 1.16 ± 0.07 s− 1 in comparison to 0.05 ± 0.003 s− 1 for a hydrous nickel oxide electrode not subjected to ageing.