Banana Peel-Derived Activated Carbon/MnO₂ Composites for Supercapacitor Electrode Applications

Banana peel waste is an abundant agricultural by-product with high carbon content but remains largely underutilized. This study presents a preliminary investigation into the conversion of banana peel waste into activated carbon and its integration with manganese dioxide (MnO₂) to produce biomass-derived composite electrodes for supercapacitor applications. Activated carbon was prepared by carbonization followed by chemical activation using 30 wt% H₃PO₄, while MnO₂–carbon composites were synthesized hydrothermally at 120 °C for 4 h using different carbon-to-MnO₂ mass ratios. The composites were characterized by Brunauer–Emmett–Teller (BET) analysis, and their electrochemical performance was evaluated by cyclic voltammetry (CV) in a three-electrode system with 6 M KOH electrolyte. Repeated measurements were conducted to improve data reliability. Among the investigated samples, MnO₂–BAC–1 exhibited the highest average specific capacitance of 108.87 F g⁻¹ at a scan rate of 0.05 V s⁻¹, which corresponded to the largest pore volume. Although the present findings are limited to BET and CV analyses, they demonstrate the feasibility of utilizing banana peel waste as a sustainable precursor for MnO₂–carbon composite electrodes and provide a basis for further structural characterization and comprehensive electrochemical evaluation.