No abstract

The present work reports the synthesis of biomass derived activated carbon and its electrochemical behaviour in different electrolytes. Ricinus communis shell (RCS) was used as a raw material in this study for the synthesis of activated carbon (AC) following a high-temperature activation procedure using potassium hydroxide as the activating agent. The physical and structural characterization of the prepared Ricinus communis shell-derived activated carbon (RCS-AC) was carried by Brunauer-Emmett-Teller analysis, X-ray diffraction analysis, Fourier Transform Infrared Spectroscopy, Raman Spectroscopy and Scanning Electron Microscopy. The synthesized AC was electrochemically characterized using various techniques such as Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) tests, and Electrochemical impedance spectroscopy (EIS) measurements in different aqueous electrolytes (KOH, H2SO4, and Na2SO4). The results show that the double layer properties of the RCS-AC material in different electrolytes are distinct. In specific, the working electrode tested in 3 M KOH showed excellent electrochemical performance. It demonstrated a specific capacitance of 137 F g−1 (at 1 A g−1 in 3 M KOH) and exhibited high energy and power densities of 18.2 W hkg−1 and 663.4 W kg−1, respectively. The observed capacitance in 3 M KOH remains stable with 97.2% even after 5000 continuous charge and discharge cycles, indicating long-term stability. The study confirmed that the synthesized RCS-derived activated carbon (RCS-AC) exhibits good stability and physicochemical characteristics, making them commercially promising and appropriate for energy storage applications.

Due to its abundant availability, eco-friendliness, and high sustainability, biomass-derived acti­vat­ed carbon has captured more attention in recent years. In this study, activated carbon was derived from Palmyra palm flowers (PPF) using a conventional chemical activation process and carbo­nization at different ambient temperatures, viz. 700, 800, and 900 °C. The carbonized PPF was chemically activated using 1 wt.% potassium hydroxide to increase the microporosity and specific surface. The experimental data were analyzed using an X-ray diffractometer (XRD), scanning elec­tron microscopy (SEM), energy-dispersive X-ray spectrometer (EDX), Raman spectr­oscopy and Fourier transform infrared spectroscopy (FT-IR). The nitrogen adsorption/de­sorption isotherm curve for activated carbon synthesized at the activation temperature of 900 °C indicated type IV with a hysteresis loop associated with mesopores formation and a specific surface area of 950 m2g-1. The supercapacitor electrodes made with PPF-derived carbon were evaluated for their electrochemical performance by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge measurements. In the aqueous electrolyte (3 M KOH), electro­chemical experiments showed that PPF-900 electrode has a specific capacitance of 155 F g-1 at 1 A g-1 and significant cyclic stability (97.3 % capacitance retention over 5000 cycles at 10 A g-1), while energy and power densities were estimated as 15.1 Wh kg-1 and 100.6 W kg-1. This study suggests that biowaste products could be transformed into activated carbon materials to improve the performance of energy storage materials, and it adheres to the 'waste to treasure' principle.