Electrochemical synthesis of α-cobalt hydroxide

Cathodic reduction of an aqueous solution of cobalt nitrate at low pH, high Co(II) ion concentration (greater than or equal to 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 Angstrom. This hydroxy deficient phase is structurally and compositionally related to alpha-nickel hydroxide, but likely contains Co(II) ions in a mixed octahedral/tetrahedral coordination. Under other deposition conditions, the better known beta-cobalt hydroxide (a=3.17+/-0.01 Angstrom, c=4.61 +/- 0.02 Angstrom) is obtained.