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Öğe Comparative activation of pine pollen-derived carbon with KOH and CuCl2 for high-performance supercapacitor electrodes(Springer Heidelberg, 2025) Atalay, Funda Ersoy; Kaya, Harun; Korkmaz, Aydan Aksogan; Gokturk, Gunay; Guler, SeherBiomass-derived porous carbons have emerged as promising candidates for high-performance supercapacitor electrodes owing to their low cost, sustainability, and tunable physicochemical properties. In this work, pine pollen, an abundant and underutilized natural precursor, was converted into porous carbon via hydrothermal carbonization followed by chemical activation using KOH and CuCl2. A systematic comparison of these activation agents was conducted to elucidate their effects on structural, morphological, and electrochemical characteristics. KOH activation produced carbon with a high specific surface area of 2030.32 m2/g and a specific capacitance of 230 F/g at 5 A/g, while CuCl2 activation yielded carbon with a surface area of 736.8 m2/g and a capacitance of 176 F/g. After 5000 charge-discharge cycles, capacitance retention was 76% for the KOH-activated electrode and 93% for the CuCl2-activated counterpart. This study provides the first comprehensive insight into the role of activation chemistry in tailoring pine pollen-derived carbon for supercapacitor applications, demonstrating the potential of pine pollen as a sustainable and low-cost resource for advanced energy storage systems.Öğe Electrode material development from natural specularite ore for supercapacitor applications(Springer Heidelberg, 2025) Kaya, Harun; Korkmaz, Aydan Aksogan; Guler, Seher; Atalay, Funda ErsoyNatural specularite ore was investigated as a sustainable and low-cost raw material for supercapacitor electrodes. This study provides new insight by demonstrating the direct conversion of an abundant iron ore into a functional nanostructured electrode (nano sp/NF) through a combined process of planetary ball milling, ultrasonic exfoliation in N, N-dimethylformamide, and hydrothermal treatment. The fabricated electrode exhibited a specific capacitance of 425 F/g at 20 A/g together with remarkable cycling stability over 10,000 charge-discharge cycles. These superior performances are associated with the enlarged surface area and porous architecture, which facilitate rapid ion transport and efficient Faradaic reactions. Overall, the findings highlight the originality of employing natural ores through environmentally friendly and scalable processing routes, offering a promising pathway toward next-generation energy storage electrodes.Öğe Preparation and characterization of activated carbon from tomato, pepper, and eggplant wastes by two-step KOH activation(Taylor & Francis Inc, 2026) Yavuz, Bahar; Aksogan Korkmaz, Aydan; Kaya, Harun; Guler, Seher; Atalay, Funda ErsoyThis study investigates the morphological, structural, and chemical properties of activated carbons synthesized from common lignocellulosic agricultural wastes such as tomato, pepper, and eggplant residues. A two-step chemical activation method was employed. In the first step, the biomass was carbonized at 500 degrees C for 1 h to produce biochar. In the second step, the activation process was conducted at 800 degrees C for 1 h using different biochar:KOH impregnation ratios (1:1, 1:2, 1:3). The surface area of the resulting porous carbonaceous materials was determined by BET analysis, while their morphological features were examined by Scanning Electron Microscopy (SEM). Structural and chemical properties were characterized using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The highest surface area values of activated carbons (2070-2254 m2/g) were obtained with a biochar:KOH weight ratio of 1:3. SEM images revealed the formation of a well-developed porous structure as a result of oxidation-reduction reactions. XRD analysis indicated the presence of graphite-like amorphous structures. FTIR spectra confirmed the presence of various surface functional groups, including C = C, C = O, C-H, C-C, and C-O. These findings demonstrate that widely available and low-cost agricultural wastes can serve as effective, environmentally friendly, and sustainable precursors for the production of activated carbon.Öğe Structural and electrochemical evaluation of ball-milled natural specularite ore for supercapacitor applications(Elsevier Science Sa, 2026) Korkmaz, Aydan Aksogan; Kaya, Harun; Guler, Seher; Atalay, Funda ErsoyThe widespread availability, high theoretical specific capacitance, and low cost of transition metal oxides, such as iron, make them promising candidates for electrode materials in energy storage applications. Among these nanostructured iron oxides, hematite is a highly preferred material for supercapacitor anodes due to its low cost, non-toxicity, high abundance, and the availability of various oxidation states. This study investigates the unique characteristics of natural (raw) specularite ore, also known as mica hematite, as a supercapacitor electrode material. We employed manual grinding and ball milling methods to reduce the particle size of specularite ore. The sample's morphological, chemical, and structural characteristics were analyzed using XRF, DTA/TGA, XRD, BET, and SEM/EDX, revealing its distinct properties that set it apart from other materials. The electrochemical properties of the specularite ore, ground to the nanoscale using a ball mill, were rigorously evaluated through cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. The results showed that the specularite electrode exhibited pseudo-capacitive characteristics, with a specific capacitance of 80.6 F g-1 and a stable initial capacitance of 50 F g-1 after 1000 cycles. These findings have significant implications for the practical use of specularite in energy storage applications.
