Electrochemical synthesis of α-cobalt hydroxide

Cathodic reduction of an aqueous solution of cobalt nitrate at low pH, high Co(II) ion concentration (â 1 M) and low current densities (< 0.3 mA cm-2) leads to the formation of a novel layered hydroxide of Co(II) with an interlayer spacing of 8.93 à . This hydroxy deficient phase is structurally and compositionally related to α-nickel hydroxide, but likely contains Co(II) ions in a mixed octahedral/tetrahedral coordination. Under other deposition conditions, the better known β-cobalt hydroxide (a= 3.17±0.01 à , c = 4.61 ± 0.02 à ) is obtained.