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

Abstract

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∼3043 m2·g−1), microporous surface area (2747∼2831 m2·g−1), and higher micropore volume (1.4250∼1.4316 cm3·g−1). The as-prepared samples exist in the form of spherical-shaped particles with the size ranging from 20 to 60 nm and contain numerous surface functional groups. The as-prepared activated carbons were then assessed as an electrode material of supercapacitor operating in the 0.5 M K2SO4 electrolyte in potential windows of −1.0∼0.0 V. The highest capacitance obtained was 205 F·g−1 at the scan rate of 2 mV·s−1 and 225 F·g−1 at a current density of 0.2 A·g−1. At the scan rate as high as 50 mV·s−1, all the as-prepared activated carbons in this study have the specific capacitance greater than 100 F·g−1.

Application of microwave-induced plasma for extremely fast synthesis of large surface area activated carbon

“…[8][9][10][11][12] Activated carbon can be produced by heating carbon precursors with activating agents, such as KOH, NaOH, and K 2 CO 3 at an elevated temperature. [13][14][15][16][17][18] Nowadays, in industries, the process to prepare activated carbon is limited to only batch operation because of its long activation time. [19][20][21][22][23] The reduction of activation time can make an evolutional change in reactor design concept for activated carbon preparation by switching the batch operation to continuous operation.…”

Self-Doped Sulfur Enhanced the Activity of Fe-N for Oxygen Reduction Reaction

“…After raising the reaction temperature to 700 °C, some K 2 O was also formed. 37,38 Finally, at 800 °C, after the decomposition of K 2 O, only metallic K species remained after pyrolysis, which can be released by sublimation from in situ-formed carbon structures to create micro-and mesopores. 39 At the end of this process, the pyrolyzed product Fe-N/S-C was washed by 0.5 M H 2 SO 4 aqueous solution and DI water to remove unbound metal and impurities.…”

Potassium‐Ion Activating Formation of Fe−N−C Moiety as Efficient Oxygen Electrocatalyst for Zn‐Air Batteries

“…Moreover, compared with NaCl template, KCl is easily reduced to metallic K to intercalate into the carbon lattices of the carbon matrix during the high temperature pyrolysis process. The lower melting point of KCl (770 °C) than NaCl (801 °C) make it easier for K atom to diffuse in to the layers of the carbon, resulting in the creation of more porous structure and defects [53,57,58] . After removal of the potassium‐related compounds, the expanded carbon lattices are unable to recover, leading to more defect sites for single iron atom to anchor [59,60] .…”