Preparation of Pore-Size Controllable Activated Carbon from Rice Husk Using Dual Activating Agent and Its Application in Supercapacitor

Activated carbons prepared from rice husk by chemical activation with dual activation agents, KOH and NaOH, have been studied and characterized by BET, SEM, EDX, FTIR, Boehm titration, Raman, and TGA. It was found that the KOH/NaOH impregnation ratio plays an important role on textural properties of AC. At the same amount of total alkali hydroxide, the KOH/NaOH ratio higher than 1.33 resulted in larger specific surface area (2990 approximate to 3043m), microporous surface area (2747 approximate to 2831m), and higher micropore volume (1.4250 approximate to 1.4316cm). The as-prepared samples exist in the form of spherical-shaped particles with the size ranging from 20 to 60nm and contain numerous surface functional groups. The as-prepared activated carbons were then assessed as an electrode material of supercapacitor operating in the 0.5MK(2)SO(4) electrolyte in potential windows of -1.0 approximate to 0.0V. The highest capacitance obtained was 205F at the scan rate of 2mV and 225F at a current density of 0.2A. At the scan rate as high as 50mV, all the as-prepared activated carbons in this study have the specific capacitance greater than 100F.