Influence of Controlled Dopant Loading on the Structural and Morphological Characteristics of Death-Fruit Seed Carbon

The pursuit of sustainable and high-performance electrode materials continues to shape advancements in electrochemical supercapacitors. In this study, porous carbon was successfully synthesized from death-fruit seeds through carbonization and Potassium Hydroxide (KOH) activation, followed by controlled doping at 0 wt%, 3 wt%, and 5 wt%. Structural and surface properties were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analysis. All samples exhibited characteristic amorphous carbon diffraction peaks at 25° and 43°. Notably, moderate doping (3 wt%) enhanced structural ordering without introducing undesirable crystalline phases, while higher doping (5 wt%) led to structural strain and partial pore obstruction. Surface areas increased from 450 m² g⁻¹ (C-0%) to 750 m² g⁻¹ (C-5%); however, morphological analysis revealed that excessive doping caused particle agglomeration, limiting effective ion-accessible surface. The 3 wt% doped sample provided the best balance between crystallinity and pore accessibility. These findings highlight the importance of optimizing dopant concentration in biomass-derived carbon electrodes for improved supercapacitor performance. It is recommended that a 3 wt% dopant level be adopted to maximize supercapacitor performance while maintaining the economic and environmental benefits of this green synthesis route.