MSc Thesis Defense: Oluwatosin Johnson Ajala, VALORIZATION OF DISCARDED CIGARETTE BUTTS INTO HIGH-PERFORMANCE CARBON ELECTRODES FOR SUPERCAPACITORS, Date & Time: 14 July, 2026 – 11:30 AM, Place: FENS 2019
VALORIZATION OF DISCARDED CIGARETTE BUTTS INTO HIGH-PERFORMANCE CARBON ELECTRODES FOR SUPERCAPACITORS
Oluwatosin Johnson Ajala
Materials Science and Nano Engineering, MSc Thesis, 2026
Thesis Jury
Prof. Emre ERDEM (Thesis Advisor)
Assoc. Prof. Feray BAKAN MISIRLIOĞLU
Prof. Mustafa TUNCER
Date & Time: 14th July, 2026 – 11:30 AM
Place: FENS 2019
Zoom Link: https://sabanciuniv.zoom.us/j/
Keywords : Cigarette butt, activated carbon, supercapacitor, pyrolysis, KOH activation and defect engineering
Abstract
Cigarette butt (CB), which are persistent cellulose acetate–based wastes, were valorized into activated carbon electrodes (AC) for supercapacitor applications through controlled pyrolysis followed by KOH activation. AC derived from CB was prepared at pyrolysis temperatures of 400, 450, 500, and 600 °C to investigate the influence of pyrolysis temperature on pore development, structural ordering, paramagnetic defect formation, and electrochemical charge-storage performance. Characterization by XRD, SEM, TGA, BET, Raman spectroscopy, and EPR confirmed the formation of turbostratic porous carbon with temperature-dependent textural and defect properties. Among the prepared samples, AC-500 exhibited the most favorable structure, with the highest BET surface area of 426.29 m² g⁻¹, total pore volume of 0.231 cm³ g⁻¹, and micropore volume of 0.104 cm³ g⁻¹. Raman analysis showed that AC-500 possessed the lowest (ID/IG) ratio of 0.671 and the narrowest G-band width, indicating a relatively coherent sp² carbon framework, while EPR revealed pronounced oxygen-influenced paramagnetic defect centers with a g-factor of 2.0058 and a linewidth of 12.74 mT. Electrochemical evaluation demonstrated that AC-500 delivered the highest specific capacitance of approximately 840 F g⁻¹ at 10 mV s⁻¹, an energy density of 116 Wh kg⁻¹, and a power density of 44.54 kW kg⁻¹, with nearly 99% capacitance retention after 10,000 charge–discharge cycles. The enhanced performance is attributed to the optimized balance between hierarchical porosity, graphitic coherence, EPR-active defect centers, improved ion accessibility, and reduced internal resistance. This study establishes pyrolysis temperature as a key parameter for engineering waste-derived carbon electrodes and demonstrates the potential of discarded CB as sustainable precursors for high-performance supercapacitor materials.