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 α‐Co(OH) 2 two‐dimensional ultrathin nanosheets. The layered hydrotalcite‐like α‐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 α‐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 F g –1 at a current density of 5 mA cm –2 and maintains 48 % of the capacitance when the current density is as high as 50 mA cm –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 α‐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.