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This study introduces a gamma pretreatment of water hyacinth powder for activated carbon (AC) production with improved electrochemical properties for supercapacitor applications. The structural and morphological changes of post-irradiation were meticulously analyzed using scanning electron microscopy (SEM), Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) analysis, and X-ray photoelectron spectroscopy (XPS). The pretreatment significantly modifies the pore structure and reduces the particle size of the resulting activated carbon (WHAC). Nitrogen adsorption-desorption isotherms indicated a substantial increase in micropore volume with escalating doses of gamma irradiation. Electrochemically, the activated carbon produced from pretreated WH at 100 kGy exhibited a marked increase in specific capacitance, reaching 257.82 F g -1 , a notable improvement over the 95.35 F g -1 of its untreated counterpart, while maintaining 99.40% capacitance after 7000 cycles. These findings suggest that gamma-pretreated biomasses are promising precursors for fabricating high-performance supercapacitor electrodes, offering a viable and environmentally friendly alternative for energy storage technology development.

Activated carbons (ACs) were developed from palm petiole via a new eco-friendly method composed of highly diluted H 2 SO 4 hydrothermal carbonization and low-concentration KOH-activating pyrolysis followed by gamma-induced surface modification under NaNO 3 oxidizing environment. The prepared graphitic carbons were subsequently used as an active material for supercapacitor electrodes. The physiochemical properties of the ACs were characterized using field emission scanning electron microscope-energy dispersive X-ray spectroscopy, N 2 adsorption/desorption isotherms with Brunauer-Emmett-Teller surface area analysis, Fourier transform infrared spectroscopy, X-ray diffraction and Raman spectroscopy. The electrochemical performance of the fabricated electrodes was investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. Even treated with extremely low H 2 SO 4 concentration and small KOH:hydrochar ratio, the maximum S BET of 1365 m 2  g -1 for an AC was obtained after gamma irradiation. This was attributed to radiation-induced interconnected network formation generating micropores within the material structure. The supercapacitor electrodes exhibited electric double-layer capacitance giving the highest specific capacitance of 309 F g -1 as well as excellent cycle stability within 10,000 cycles. The promising results strongly ensure high possibility of the eco-friendly method application in supercapacitor material production., (© 2023. Springer Nature Limited.)