KOH-activated porous carbon from Mucuna monosperma seeds for supercapacitor applications

Abstract

Biomass-derived activated carbon has emerged as a promising low-cost and sustainable electrode material for electrochemical energy storage applications. In this work, activated carbon was synthesized from Mucuna monosperma seed biomass via chemical activation with potassium hydroxide (KOH), followed by carbonization and activation at 700°C to develop a porous carbon structure (BSC_700). Physicochemical characterization using iodine number, methylene blue adsorption, Boehm titration, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) confirmed the formation of predominantly amorphous carbon with well-developed porosity and surface functional groups, with a specific surface area of 1360 m² g⁻¹ estimated by using the multi-point methylene blue adsorption technique. The electrochemical performance of the prepared activated carbon was evaluated in a three-electrode configuration using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy with 6 M KOH as the electrolyte. The electrode exhibited electrical double-layer capacitive behavior and delivered a good specific capacitance of 333.8 Fg⁻¹ at 1 Ag⁻¹, demonstrating good electrochemical reversibility and low internal resistance. These results indicate that Mucuna monosperma seed- derived activated carbon is an efficient, environmentally friendly, and promising electrode material for supercapacitor applications.