Biowaste‐Derived Porous Carbon from <i>Lagenaria siceraria</i> for High‐Performance Supercapacitor Electrodes

This study investigates the synthesis of hierarchical porous activated carbon (AC) from Lagenaria siceraria (calabash) agricultural waste through a carefully controlled potassium hydroxide (KOH) activation process. By utilizing this abundant agricultural byproduct, the research provides a sustainable and cost‐effective method for creating a supercapacitor electrode. The activation process significantly boosts the material's properties, leading to a threefold increase in specific capacitance compared to unactivated biochar. This enhancement is due to the development of a high surface area of 976 m 2 g −1 and an optimized pore size distribution. The observed specific capacitance of 598 F g −1 at 1 A g −1 highlights the efficacy of KOH activation in tailoring the microporous structure for efficient ion transport and charge storage. The supercapacitor achieves an energy density of 26 Wh kg −1 in a 1 M H 2 SO 4 electrolyte. Electrochemical characterization reveals exceptional performance, with 95% capacitance retention after 10,000 cycles. These findings demonstrate a sustainable pathway for producing high‐performance supercapacitor electrodes from abundant agricultural waste.