Gamma-induced interconnected networks in microporous activated carbons from palm petiole under NaNO₃ oxidizing...

Activated carbons (ACs) were developed from palm petiole via a new eco-friendly method composed of highly diluted H₂SO₄ hydrothermal carbonization and low-concentration KOH-activating pyrolysis followed by gamma-induced surface modification under NaNO₃ 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, N₂ 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 H₂SO₄ concentration and small KOH:hydrochar ratio, the maximum S_BET of 1365 m² 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.