Abstract

To address the growing demand for high-capacitance supercapacitor electrodes, this study introduces a solvent-controlled gamma surface engineering approach to enhance nitrogen functionality and microporosity in durian shell–derived activated carbon/polyaniline composites. Activated carbon was first subjected to gamma irradiation in ethanol or ethylene glycol to induce solvent-dependent surface modification, followed by a second irradiation step to promote polymer–carbon interfacial interactions, yielding polymer-composite activated carbons (PCACs). X-ray photoelectron spectroscopy revealed a strong dependence of nitrogen and oxygen speciation on irradiation dose and solvent environment. Notably, moderate irradiation in ethanol favored the formation of imine-type nitrogen (–N=C) while maintaining an accessible microporous structure. Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, and N<inf>2</inf> sorption analyses further confirmed solvent-regulated chemical bonding, morphology, and pore characteristics, with specific surface areas reaching 1185.5 m2 g−1. Raman spectroscopy and X-ray diffraction indicated comparable structural ordering across samples. Electrochemical evaluations demonstrated that the ethanol-treated sample irradiated at 50 kGy (PEt50) achieved the optimal electrochemical performance, delivering a specific capacitance of 325 F g−1. This performance arises from the synergistic and non-linear interplay between regulated nitrogen functionality, and accessible microporosity, rather than from any single structural parameter. These results highlight solvent-controlled gamma irradiation as an effective strategy for tailoring biomass-derived carbon electrodes for advanced supercapacitor applications.