Synthesis of highly activated polybenzene-grafted carbon nanoparticles for supercapacitors assisted by solution plasma

Abstract

The growing demand for electronic storage devices with faster charging rates, higher energy capacities, and longer cycle lives has led to significant advancements in supercapacitor technology. These devices typically utilize high-surface-area carbon-based materials as electrodes, which provide excellent power densities and cycling stability. However, challenges such as inadequate electrolyte interaction, hydrophobicity that impedes ion transport, and high manufacturing costs restrict their effectiveness. This study aims to enhance carbon-based materials by grafting polymer chains onto their surfaces for supercapacitor applications. A simple solution plasma process (SPP), followed by heating, prepared the polymer-grafted carbon materials. Carbon nanoparticles were synthesized from benzene through plasma discharge in liquid under ambient conditions, forming free radical sites on the carbon surface. Subsequently, benzene molecules were grafted onto the surface via radical polymerization during heating. We investigated the structural and morphological properties of the synthesized materials using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and Raman spectroscopy. Additionally, N₂ absorption–desorption isotherms were measured, pore structure was analyzed with the Dubinin–Astakhov (DA) average pore size model, and specific surface area was determined using the Brunauer–Emmett–Teller (BET) equation for all synthesized samples. The results indicated that the grafting process was influenced by heating time and drying temperature. Furthermore, the electrical properties of the samples were evaluated using cyclic voltammetry (CV), which demonstrated enhancements in both areal capacitance and cycling stability for the polybenzene-grafted carbon compared to the non-grafted variant. This research illustrates that polymer grafting can effectively improve the performance and stability of carbon-based materials for supercapacitor applications. Future work will aim to optimize these materials for broader applications.