Factors governing the electrochemical synthesis of alpha-nickel (II) hydroxide

The electrodeposition of alpha-nickel hydroxide is promoted by the simultan eous chemical corrosion of the electrode by an acidic nitrate bath. Chemica l corrosion results in the formation of a poorly ordered layered phase whic h is structurally similar to alpha-nickel hydroxide and provides nucleation sites for the deposition of the latter. Therefore under conditions which e nhance corrosion rates such as low current density (< 1.3 mA cm(-2)), high temperature (60 circle C), high nickel nitrate concentration (greater than or equal to 1 M) and the resultant low pH (similar to 1.7), alpha-nickel hy droxide electrodeposition is observed, while beta-nickel hydroxide forms un der other conditions. Further, alpha-nickel hydroxide deposition is more fa cile on an iron electrode compared to nickel or platinum.