Akademik Veri Yönetim Sistemi
ChemistrySelect, cilt.11, sa.8, 2026 (SCI-Expanded, Scopus)
Hazelnut shell–derived activated carbons were synthesized via phosphoric acid chemical activation and subsequently modified using microwave (MW) and ultrasonic (US) treatments to tailor their physicochemical and electrochemical properties for supercapacitor applications. Structural and spectroscopic analyses confirmed the formation of turbostratic carbon frameworks with partial graphitic ordering and abundant surface functional groups. Elemental analysis revealed that microwave treatment induced pronounced surface oxidation, whereas ultrasonic treatment preserved high carbon content while introducing moderate oxygen functionalities. Thermal analysis demonstrated superior thermal stability for the ultrasound-assisted activated carbon. Electrochemical performance was evaluated in a three-electrode system using 3 M KOH electrolyte. Cyclic voltammetry revealed dominant electrical double-layer capacitive behavior with minor pseudocapacitive contributions, particularly for the ultrasound-treated sample. Among all electrodes, ACA-US exhibited the largest CV area, highest current response, and superior specific capacitance, attributed to its exceptionally high BET surface area (2138 m2 g−1) and well-developed microporosity. Galvanostatic charge–discharge measurements confirmed excellent reversibility and rate capability, with ACA-US delivering the longest discharge times and highest capacitance over a wide current density range. Electrochemical impedance spectroscopy revealed reduced charge transfer resistance and improved ion diffusion kinetics for ACA-US. Furthermore, the optimized electrode retained ∼85% of its initial capacitance after 2000 cycles, indicating excellent long-term stability. These results demonstrate that ultrasonic post-treatment is an effective strategy for producing high-performance biomass-derived activated carbons for advanced supercapacitor applications.