Electrochemical synthesis of α-cobalt hydroxide

Abstract

Cathodic reduction of an aqueous solution of cobalt nitrate at low pH, high Co(II) ion concentration (≥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 Å. 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 Å, c=4.61±0.02 Å) is obtained.