Facile electrochemical synthesis of uniform β-Co(OH)2 nanoplates for high performance supercapacitors

Abstract

Uniform cobalt hydroxide nanoplates were prepared via pulse cathodic electrodeposition and their electrochemical performance was investigated using cyclic voltammetry and charge–discharge tests. The deposition experiments were performed in the pulse current (PC) mode by applying typical on-times and off-times (ton=5s and toff=10s). The mechanism of deposit formation and growth on the cathode surface is discussed in detail. The obtained deposit was characterized by CHN, XRD, IR, BET, SEM and TEM techniques. The analyses results revealed that the obtained deposit has a single phase of the hexagonal brucite-like β-Co(OH)2 which is composed of completely uniform nanoplates with angles of adjacent edges of 120° and edge lengths ranging from 200 to 300nm. The supercapacitive investigation by cyclic voltammetry and charge–discharge tests showed that the prepared nanoplates have high contribution of active materials in the redox reactions where they presented a high specific capacitance of 1012.7Fg−1 at current density of 2Ag−1 and an excellent cycling stability of 92% capacity retention after 1000 cycling. The average coulombic efficiencies of 99.5%, 94% and 90% were also observed for the 10th, 500th and 1000th charge–discharge cycles at the applied current density of 2Ag−1. These findings verified the promising application of the prepared nanoplates as an electrode material for supercapacitors.