Studies on the capacitance of nickel oxide films : Effect of heating temperature and electrolyte concentration

Nickel oxide films were prepared by electrochemically precipitating the hydroxide and heating it in air to form the oxide. The resulting oxide films behave as a capacitor. The capacitance of the oxide depends on the heating temperature, showing a maximum at 300 C. The mechanism of charge storage was studied by measuring the capacitance and surface area as a function of heating temperature, and the capacitance in different electrolytes and potential windows. The charge-storage mechanism is believed to be a surface redox reaction involving adsorbed hydroxyl ions.