Microwave-assisted rapid activation of carbon nanoparticles for symmetrical supercapacitor electrode

The present work is an attempt to one-step synthesis of carbon nanoparticles (CNPs) using a mustard oil lamp with a cotton wick. Then, CNPs have been used to a rapid microwave-assisted activation (400 W, 3 min) with KOH for producing activated carbon nanoparticles (ACNPs). As prepared CNPs and ACNPs have been examined as electrode materials for symmetrical supercapacitors (SSCs). The CNPs and ACNPs have been characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy, and scanning electron microscopy (SEM) with EDX elements mapping, and Brunauer-Emmett-Teller (BET). The surface analysis has revealed the spherical morphology with an average size of ∼62 and 72 nm for CNPs and ACNPs, respectively. Further, CNPs and ACNPs have been tested as electrode materials in SSCs, using 6 M KOH as the electrolyte. The electrochemical evaluation confirmed that ACNPs exhibited superior performance compared to CNPs, achieving a specific capacitance of 326.14 F/g at 3 A/g and 480.6 F/g at 10 mV/s. Additionally, the cycling tests at 100 mV/s demonstrated excellent capacitance retention of 83.2 % after 2000 cycles, with an energy density of 16.30 Wh kg⁻¹ and a power density of 771.42 Wkg⁻¹. Results show that the present method offers an efficient strategy for high-yield ACNPs, notably enhancing the electrochemical performance of fabricated SSCs.