Large-Scale and Facile Electrochemical Preparation of β-Co(OH)₂Nanocapsules and Investigation of their Supercapacitive Performance

A novel nanostructure of cobalt hydroxide (i.e. nanocapsule) was prepared via cathodic electrodeposition and its electrochemical performance was investigated using cyclic voltammetry and charge-discharge tests. The deposition experiments were performed in the pulse current mode (t on = 10 ms and t off = 10 ms) with applying the current density of 1 mA cm −2 at low bath temperature of 10°C. The structural and morphological characterization by XRD, IR, SET, TEM and BET techniques showed that the obtained deposit has single crystalline β phase of Co(OH) 2 with high surface area capsule-like morphology. Mechanism of the β-Co(OH) 2 nanocapsules was proposed and discussed. The electrochemical measurements displayed that the nanocapsules are capable to deliver specific capacitances of 1243.1, 1170.8, 1050.5 and 908.5 Fg −1 at the scan rates of 2, 5, 10 and 25 mV s −1 , respectively, within the potential range of −0.25−0.55 V (vs. Ag/AgCl). The results confirmed an excellent contribution of the nanocapsules in the redox reactions, suggesting the potential application in electrochemical supercapacitors.