Magnetized biochar from Gracilaria spinulosa for enhanced electrochemical performance in supercapacitors: synthesis, characterization and application

Abstract The increasing demand for sustainable energy storage has driven the search for new electrode materials for supercapacitors (SCs). Biochar, a promising carbon rich electrode material for supercapacitor due to its excellent porosity, higher surface area, stability, renewability, sustainability and cost-effectiveness. This study focused on preparation of magnetized biochar from Gracilaria spinulosa red algae as alternative electrode materials in supercapacitors. Various physicochemical analysis techniques were used to characterize the obtained materials, including SEM, TEM, EDS, FTIR, Raman spectroscopy, BET, VSM and XRD. The investigation demonstrated that appropriate integration of iron oxide nanoparticles increased the conductivity and surface characteristics of the material. Further, the electrochemical characteristics were evaluated using cyclic voltammetry (CV), Galvanostatic Charge–Discharge (GCD) and electrochemical impedance spectroscopy (EIS) analysis. The synthesized magnetized biochar exhibited a specific capacitance of 45.90 F g −1 with good cycling stability at a current density of 0.5 A g −1 and maintained 75% of its initial capacitance over 500 cycles. Likewise, it has showed a decreased internal resistance and promoted ion transfer owing to its magnetic properties. Thereby, the magnetized biochar from Gracilaria spinulosa can act as a viable and environmentally friendly electrode material for supercapacitors.