Activated Carbon by KOH and NaOH Activation: Preparation and Electrochemical Performance in K2SO4 and Na2SO4 Electrolytes

Activated carbons were successfully prepared from rice husk (RH) by chemical activation using KOH (RH-K4) or NaOH (RH-N3) as activating agents and characterized by means of SEM, EDX, FTIR, Raman, Boehm titration, and TGA methods. The as-prepared activated carbon samples are composed of spherical particles with lots of cracks and crevices as showed in SEM images. They have numerous surface functional groups which proofed by FTIR and Boehm titration. Raman result revealed that the crystalline size along basal plane (L-a) of RH-K4 and RH-N3 are 3.27 and 3.46 nm, respectively, which demonstrated the higher disorder degree of RH-K4 compared to RH-N3. Cyclic voltammetry and charge-discharge tests exhibit the electric double layer capacitor characteristic of the electrodes. RH-K4 shows a better performance at low scan rate and current density, whereas RH-N3 is superior at high scan rate and current density. At all experimental conditions studied, the as-prepared electrodes behave better in K2SO4 electrolyte than in Na2SO4 electrolyte.