Green synthesis of durian shell-derived activated carbon with enhanced carboxylic functionalization and graphitization via gamma irradiation in ethanol and ethylene glycol for supercapacitor applications

This study investigates the synthesis of durian shell-derived activated carbon (AC) with enhanced carboxylic functionalization and graphitization using a green approach, gamma irradiation in ethanol (Et) and ethylene glycol (EG) scavengers. The surface chemistry through X-ray photoelectron spectroscopy (XPS) revealed an increase in -COOH groups upon irradiation in both scavengers. Fourier transform infrared (FTIR) spectroscopy further confirmed the presence of the oxygenated functional groups, supporting the XPS data. Field emission scanning electron microscope (FESEM) analysis highlighted scavenger-specific morphological differences. N-2 adsorption-desorption and S-BET measurements clearly indicated the effects of dose and scavenger type on the textural properties of the materials, showing the maximum specific surface area of 1271.4 m(2) g(-1) after irradiation. Raman spectroscopy and X-ray diffraction (XRD) analysis indicated high graphitization (I-D/I-G similar to 0.84-0.85), unaffected by irradiation dose or scavenger type, suggesting that EG and Et can highly enhance graphitization compared to other scavenging systems. Electrochemical tests based on cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) demonstrated that the development of -COOH groups significantly enhanced charge storage capacity providing the highest specific capacitance of 266.7 F g(-1) with reduced internal resistance. The results emphasized the synergistic effects of radiation dose and scavenger type on the AC properties, enhancing its performance for supercapacitor applications.