Synthesis and electrochemical capacitance of sheet-like cobalt hydroxide

Cobalt hydroxide was synthesized via a new approach, in which the gel was prepared by the reaction of Co(NO3)2 solution with citric acid, and then the precursors were obtained after thermal treatment, finally the precursors reacted with KOH solution to produce the samples. The components of the precursors were measured by Fourier transforms infrared (FT-IR) spectroscopy. The morphology and structure of samples were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The results indicate that the as-prepared materials are β-Co(OH)2 with sheet-like morphology. The effect of the treatment temperature for the precursor on sheet size was discussed in detail. Cyclic voltammetry and constant current charge/discharge measurements show that the prepared cobalt hydroxide exhibits excellent capacitance performance. The specific capacitance is up to 416.7 F g−1 at a constant current charge/discharge test of 5 mA.