Yazar "Karimi-Maleh, Hassan" seçeneğine göre listele

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    Direct utilization of radioactive irradiated graphite as a high-energy supercapacitor a promising electrode material
    (Elsevier Sci Ltd, 2022) Karimi-Maleh, Hassan; Kariper, I. Afsin; Karaman, Ceren; Korkmaz, Satiye; Karaman, Onur
    Considering ever-increasing energy needs, resulting in the depletion of fossil fuels and, as a corollary, global warming, the adoption of green technologies and the development of sophisticated energy storage and conversion technologies are imperative. Although the supercapacitors have garnered a lot of attention as a highperformance energy storage solution, it is still crucial to engineer novel electrode materials via low-cost and facile, scalable methods while maintaining their enhanced power density and cycle stability. In this work, it was aimed to design and engineer graphite (GRs)-based electrode low-cost materials to be utilized as a highperformance supercapacitor. This study is of great importance in terms of it is one of the first works which offered a facile pathway to fabricate GRs-based electrode materials via the irradiation approach, as well as direct utilization of them in supercapacitor cells. In this regard, various graphite-based samples were prepared by irradiation with several point beam radiation sources, including Am-241, Sr-90, Co-60, and Na-22. The electrochemical active surface area and microcrystalline sizes of GRs were fine-tuned via the type of the radiation source. X-Ray Diffraction (XRD), Raman spectroscopy, and Scanning Electron Microscopy, Energy Dispersive X Ray (SEM-EDX) techniques were employed to assess the physicochemical features of the as-obtained GRs. The electrochemical behaviors of the samples were further tested in 3.0 M H2SO4 aqueous electrolyte via the coin-cell type supercapacitor cells based on GRs. The maximum specific capacitance was achieved for the GR-Sr90 sample, which was of the largest electrochemically active surface area (0.3087 cm(2)), as 483.20F.g(-1) at a current density of 0.2 A.g(-1), which was roughly 5 fold of the non-irradiated GR sample. At the end of the 5,000th CV cycle, the capacitance retention of GR-Sr90 was determined to be 97.40 %. The energy density and power density values of assembled supercapacitor cells based on GRs were found to be comparable to the commercial energy storage systems. All these striking results reveal that the suggested scalable fabrication method will shed an innovative light on the development and engineering of energy storage systems based on low-cost graphite-based electrode materials.
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    Irradiated rGO electrode-based high-performance supercapacitors: Boosting effect of GO/rGO mixed nanosheets on electrochemical performance
    (Elsevier Sci Ltd, 2022) Karaman, Onur; Kariper, I. Afsin; Korkmaz, Satiye; Karimi-Maleh, Hassan; Usta, Metin; Karaman, Ceren
    Supercapacitors are seemed to be one of the most promising choices as an energy storage system. However, there is still a gap in enhancing its energy density values and cyclic stabilities throughout a facile approach. Herein, it was aimed to propose a facile and effective way to fabricate high-energy supercapacitor electrode material based on reduced graphene oxide (rGO) nanostructure. Bearing this in mind, the bulk rGO powder was irradiated by various beam sources including Co-60, Am-241, Na-22, and Sr-90, and the resultant irradiated rGO samples were utilized as the electrode active material to fabricate symmetrical supercapacitor cells. The irradiated rGO samples were characterized both physicochemically and electrochemically. The physicochemical characterizations revealed that as a consequence of the irradiation, both GO and rGO nanosheets were formed in the resultant powder and the d-spacing of the graphene nanosheets were expanded. The highest electrochemical performance metrics were acquired for Sr-90 irradiated rGO electrode-based supercapacitor cell with the specific capacitance value of 585.44F.g ? 1 at 0.2 A.g ? 1, and outstanding capacitance retention performance of 97.14% for the 5000th CV cycles at 200 mV.s ? 1. Moreover, the energy density and power density values were comparable to other commercial energy storage systems such as lead-acid and nickel-metal hybrid batteries. Hence, it can be speculated that these pioneering breakthroughs could pave the way for cutting-edge high-energy supercapacitors based on rGO-derivatives with superior electrochemical performance metrics, as well as engineering of highperformance rGO-based materials to be employed in various energy applications.