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

Abstract

The electrodeposition of α-nickel hydroxide is promoted by the simultaneous chemical corrosion of the electrode by an acidic nitrate bath. Chemical corrosion results in the formation of a poorly ordered layered phase which is structurally similar to α-nickel hydroxide and provides nucleation sites for the deposition of the latter. Therefore under conditions which enhance corrosion rates such as low current density (<1.3 mA cm−2), high temperature (60 ∘C), high nickel nitrate concentration (≥ 1M) and the resultant low pH (∼1.7), α-nickel hydroxide electrodeposition is observed, while β-nickel hydroxide forms under other conditions. Further, α-nickel hydroxide deposition is more facile on an iron electrode compared to nickel or platinum.