Biomass-derived activated carbon from Cyperus pangorei for high-performance supercapacitor electrodes

Abstract

Activated carbon was successfully prepared from Cyperus pangorei through a simple and cost-effective thermal decomposition method using ghee as a carbonization aid. The obtained carbon was annealed at 500 °C for 3 h and characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). SEM analysis revealed aggregated carbon particles, while FTIR confirmed the presence of oxygen-containing surface functional groups. The electrochemical performance of the prepared carbon electrode was evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycling stability studies using PVA / Na₂SO₄ gel electrolyte within a potential window of 0–1.5 V. The electrode exhibited a maximum specific capacitance of 476 F g^-1 and maintained excellent capacitive behaviour even at a high current density of 25 A g^-1. The enhanced electrochemical performance is attributed to the combined contribution of electric double-layer capacitance and surface redox activity associated with oxygen-containing functional groups. The results demonstrate that Cyperus pangorei-derived carbon is a promising low-cost and sustainable electrode material for supercapacitor applications.