Synthesis and Exfoliation of Layered α-Co(OH)2 Nanosheets and Their Electrochemical Performance for Supercapacitors

A novel facile approach has been developed to prepare graphene-like -Co(OH)(2) two-dimensional ultrathin nanosheets. The layered hydrotalcite-like -Co(OH)(2) aggregates were successfully exfoliated in formamide solution in a constant temperature oscillator. The influence of exfoliation on the thickness and surface structure of the Co(OH)(2) monolith was analyzed by scanning electron microscopy and transmission electron microscopy. After the exfoliation process, the electrochemical performances of the 2D -Co(OH)(2) nanosheets were tested by cyclic voltammetry, galvanostatic discharge/charge, and electrochemical impedance spectroscopy. Impressively, the charge/discharge study shows that the exfoliated sample is capable of delivering a high specific capacitance of 952 Fg(-1) at a current density of 5 mAcm(-2) and maintains 48% of the capacitance when the current density is as high as 50 mAcm(-2). In addition, the exfoliated Co(OH)(2) nanosheets also exhibited excellent cycling stability and is an excellent electrode material for high-performance supercapacitors. Our work not only presents a cost-effective and scalable method for the synthesis of -Co(OH)(2) nanosheets with a high surface area, but also holds promise for the synthesis of a series of other graphene-like laminar structures with high specific surface areas for electrochemical energy storage, catalysis, gas sensing, and other applications.