Researcher:
Paksoy, Aybike

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Master Student

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Aybike

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Paksoy

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Paksoy, Aybike

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2021 - 20223

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Researcher Of Publications: search.filters.isAuthorOfPublication.6a728c08-d955-4ad4-b5c1-ef512923f990

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    Low-cost and reusable iron- and nickel-based metal boride nanoparticles for efficient catalytic hydrolysis of sodium borohydride
    (Pergamon-Elsevier Science Ltd, 2022) N/A; N/A; N/A; N/A; Department of Chemistry; Paksoy, Aybike; Öztulum, Samira Fatma Kurtoğlu; Yağcı, Mustafa Barış; Balcı, Özge; Master Student; PhD Student; Researcher; Researcher; Department of Chemistry; Koç University Boron and Advanced Materials Application and Research Center (KUBAM) / Koç Üniversitesi Bor ve İleri Malzemeler Uygulama ve Araştırma Merkezİ; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; College of Sciences; N/A; 384798; N/A; 295531
    Development of efficient catalysts for hydrogen evolution reaction is of key importance for the safe storage and utilization of hydrogen from the hydrolysis of NaBH4. In this study, a series of nanocatalysts containing iron-and nickel-based metal borides were developed through a mechanochemical route followed by a wet milling step. The use of the mole ratio of metal chlorides to NaBH4 as 1:2 enabled the simultaneous formation of Ni3B and FeB phases, while the room-temperature synthesis method caused a uniform morphology with an average particle size and surface are of 70 nm and 41.8 m2/g, respectively. This powder showed the best catalytic performance compared to other samples with a hydrogen gen-eration rate value of 758 ml H2 min-1 gcat-1 at room temperature and an activation energy of 40.8 kJ/mol. The catalyst performed good durability for each cycle and retained about 70% of its initial catalytic activity after 5 cycles. The availability of active iron, nickel, and boron species on the surface contributed to the enhancement of catalytic activity. As -prepared catalysts can be considered as low-cost and reusable materials for the efficient hydrolysis of sodium borohydride.
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    Negative additive manufacturing of Al2O3-Al cermet material by fused deposition and Direct Ink Writing
    (Elsevier, 2022) N/A; N/A; N/A; N/A; Department of Chemistry; Department of Mechanical Engineering; Shahzad, Aamir; Khan, Shaheryar Atta; Paksoy, Aybike; Balcı, Özge; Lazoğlu, İsmail; PhD Student; PhD Student; Master Student; Researcher; Faculty Member; Department of Chemistry; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; N/A; N/A; 295531; 179391
    Although additive manufacturing is an attractive alternative for the manufacturing of complex ceramic geom-etries, the manufactured parts have low mechanical properties due to low solid loading, high porosity, and geometrical distortions. Introducing ductile metal particles into the brittle ceramic matrix is an effective tech-nique to enhance the geometrical accuracy and mechanical properties of the printed part. In the current research, the Direct Ink Writing technique is used to fabricate alumina-based matrix composite reinforced with Al particles by negative additive manufacturing. A homogenous cermet mixture in the form of Al2O3-Al with various Al compositions (5 vol%, 10 vol%, 15 vol%, and 20. vol%) was achieved by high-energy ball milling. A slurry was prepared by mixing the milled powder with the carboxymethyl cellulose binder and sodium silicate in the deionized water. Rheological measurements of all the slurries were carried out to investigate the shear-thinning behavior of the pastes. The slurry was cast into the polylactic acid mold as the mold was built up layer by layer simultaneously using a Mitsubishi robotic manipulator. The printed parts were dried, demolded by dissolving in Dichloromethane (DCM) solution, and sintered at 1400 degrees C for 6 h. X-ray diffraction results revealed two distinguished phases (ceramic and metal) in the finished part. It is possible to formulate printable alumina -aluminum cermet slurries with solid content as high as 50 vol% and 97 % density. It was found that by the inclusion of metallic Al phase, the micro-hardness reduces as compared to monolithic alumina ceramic.
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    PublicationOpen Access
    Nanocrystalline cobalt-nickel-boron (metal boride) catalysts for efficient hydrogen production from the hydrolysis of sodium borohydride
    (Elsevier, 2021) N/A; Department of Chemical and Biological Engineering; Department of Chemistry; Paksoy, Aybike; Altıntaş, Zerrin; Khoshsima, Sina; Öztulum, Samira Fatma Kurtoğlu; Dizaji, Azam Khodadadi; Uzun, Alper; Balcı, Özge; Researcher; Researcher; Faculty Member; Researcher; Department of Chemical and Biological Engineering; Department of Chemistry; Koç University AKKİM Boron-Based Materials _ High-technology Chemicals Research _ Application Center (KABAM) / Koç Üniversitesi AKKİM Bor Tabanlı Malzemeler ve İleri Teknoloji Kimyasallar Uygulama ve Araştırma Merkezi (KABAM); Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Engineering; College of Sciences; N/A; N/A; N/A; N/A; N/A; 59917; 295531
    Innovative metal boride nanocatalysts containing crystalline Co-Ni based binary/ternary boride phases were synthesized and used in the hydrolysis of NaBH4. All the as-prepared catalysts were in high-purity with average particle sizes ranging between similar to 51 and 94 nm and consisting of different crystalline phases (e.g. CoB, Co2B, Co5B16, NiB, Ni4B3, Ni2Co0-67B0.33). The synergetic effect of the different binary/ternary boride phases in the composite catalysts had a positive role on the catalytic performances thus, while the binary boride containing phases of unstable cobalt borides or single Ni4B3 were not showing any catalytic activity. The Co-Ni-B based catalyst containing crystalline phases of CoB-Ni4B3 exhibited the highest H-2 production rate (500.0 mL H-2 min(-1) g(cat)(-1)), with an apparent activation energy of 32.7 kJ/mol. The recyclability evaluations showed that the catalyst provides stability even after the 5th cycle. The results suggested that the composite structures demonstrate favorable catalytic properties compared to those of their single components and they can be used as alternative and stable catalysts for efficient hydrogen production from sodium borohydride.