Preparation of Activated Carbon from Popcorn by Potassium Nitrate and Its Application in Supercapacitors

The efficient and environmentally friendly preparation of activated carbon is an important issue within the field. In the present study, fluffy biomass derived from popcorn was treated as the raw material and subsequently carbonized with the addition of potassium nitrate in ambient air. It is noteworthy that this preparation method does not employ strong bases or other environmentally harmful chemicals, such as potassium hydroxide or anhydride chloride. The prepared activated carbon was subjected to a comprehensive analysis utilizing scanning electron microscopy, transmission electron microscopy, X-ray diffraction, elemental analysis, nitrogen adsorption-desorption isotherms, Raman spectroscopy, and X-ray photoelectron spectroscopy to investigate the influence of preparation parameters and environmental conditions on the physicochemical properties. The postprocessed activated carbon was deemed suitable for the fabrication of supercapacitors. The resulting supercapacitors were evaluated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) tests to assess their electrochemical properties. The results indicated that activated carbon treated in ambient air exhibited superior surface characteristics, and the supercapacitors fabricated with this activated carbon demonstrated enhanced performance. Notably, the supercapacitor constructed with the best-activated carbon achieved the highest specific capacitance of 93.20 F/g and an energy density of 23.59 W h/kg.