Researcher:
Aksoy, Merve

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PhD Student

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Merve

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Aksoy

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Aksoy, Merve

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2020 - 20225

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Researcher Of Publications: search.filters.isAuthorOfPublication.7154535a-9bdb-4a1c-ad11-da4a768bfabb

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    The rational design of gCN/a-WOx/Pt heterostructured nanophotocatalysts for boosting the hydrogen generation from the hydrolysis of ammonia borane under visible light
    (Elsevier Ltd, 2022) N/A; Department of Chemistry; Department of Chemistry; Aksoy, Merve; Korkut, Sibel Eken; Metin, Önder; PhD Student; Researcher; Faculty Member; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; 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 Sciences; College of Sciences; N/A; N/A; 46962
    In-situ generation of platinum nanoparticles (Pt NPs) supported on graphitic carbon nitride/amorphous tungsten oxide (gCN/a-WOx) binary heterojunctions under white-light irradiation was performed during the hydrolysis of ammonia borane (HAB). The gCN/a-WOx/Pt(IV) nanocomposites including different amount of W were prepared to study their comparative photocatalysis for the photocatalytic HAB. The yielded gCN/a-WOx/Pt nanocatalysts provided a maximum turnover frequency (TOF) value of 419.2 mol H2 mol Pt−1 min−1, which is higher than that of gCN/Pt nanocatalysts (287.7 mol H2 mol Pt−1 min−1). Many advanced analytical techniques comprising ICP-MS, TEM, HAADF-STEM, XRD, XPS, EDX, and BET were used to determine the elemental composition, morphology, elemental distribution, crystal structure, chemical/oxidation state of the surface elements and the textural properties of the nanocatalysts. The characterization results support the formation of wrinkled paper-like amorphous phase WOx (a-WOx) materials in multiple oxidation states over the gCN nanosheets. The photophysical properties of gCN/a-WOx nanocomposites were also analyzed by using UV–Vis DRS, PL, and TRES techniques to clarify the contribution of the heterojunction formation between gCN and a-WOx semiconductors to the photocatalytic activity. Owing to the enhanced visible light absorption, suppressed charge recombination, and promoted charge carrier transfer, gCN/a-WOx/Pt nanocatalysts boosted the hydrogen production from the HAB under white-light irradiation by providing 419.2 mol H2 mol Pt−1 min−1 TOF, which is 4.8 times higher compared to the one obtained in dark. A plausible photocatalytic mechanism for the photocatalytic HAB reaction in the presence of gCN/a-WOx/Pt nanocatalysts was suggested based on the results of performed scavenger experiments. The rate law and the activation parameters for the of gCN/a-WOx/Pt catalyzed HAB were also reported along with kinetic studies. Additionally, a reusability test was performed to understand the stability of gCN/a-WOx/Pt nanocatalysts in the HAB such that the significance of a-WOx species in the enhancement of photocatalytic activity became more pronounced. This study reports for the first time that gCN/a-WOx heterojunctions are favorable support materials for the in-situ generation of Pt NPs and promoting the photocatalytic activity of Pt NPs in the hydrogen generation from the HAB under white-light illumination. © 2022 Hydrogen Energy Publications LLC
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    Pt nanoparticles supported on mesoporous graphitic carbon nitride as catalysts for hydrolytic dehydrogenation of ammonia borane
    (American Chemical Society (ACS), 2020) N/A; Department of Chemistry; Aksoy, Merve; Metin, Önder; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 46962
    Platinum (Pt) nanoparticles (NPs) supported on mesoporous graphitic carbon nitride (mpg-CN/Pt) were synthesized in situ via the reduction of as-prepared mpg-CN/Pt(IV) composites during the catalytic hydrolysis of ammonia-borane (AB) under the white-light irradiation. The yielded mpg-CN/Pt nanocatalysts were characterized by using many advanced analytical techniques including TEM, XRD, ICP-MS, XPS, FTIR, PL, and time-resolved emission spectroscopy (TRES) techniques. Besides the privilege advantageous of the presented in situ synthesis protocol for the synthesis of mpg-CN/Pt nanocatalysts, formation of the heterojunction between in situ generated Pt NPs and visible-light active semiconductor mpg-CN enables an improved charge separation and prolonged lifetime, resulting in 2.25-fold enhanced photocatalytic activity within the hydrolysis of AB under white-light irradiation. The effect of Pt loading on the catalytic activity of mpg-CN/Pt nanocatalysts was examined in the hydrolysis of AB and the highest turnover frequency (TOF) of 274.2 min(-1) was obtained with 5.94 wt % Pt-loaded mpg-CN/Pt nanocatalysts, which is the one of the best TOFs among monometallic Pt-based nanocatalysts and comparable to the ones reported using bimetallic Pt nanocatalysts. Moreover, mpg-CN/Pt nanocatalysts were found to be highly durable in the hydrolysis of AB such that it preserves 78% of its initial catalytic activity after the 10th consecutive runs, which is one of the highest reusability performances among all Pt-based catalysts that have been tested in the hydrolysis of AB so far. Upon the results of the kinetic studies, the rate law and activation parameters for the mpg-CN/Pt-catalyzed AB hydrolysis were also reported. This work demonstrates for the first time that mpg-CN is a proper support material for the in situ synthesis of catalytically active yet stable Pt NPs promoting the photocatalytic hydrogen evolution from the hydrolysis of AB.
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    AuPt alloy nanoparticles supported on graphitic carbon nitride: in situ synthesis and superb catalytic performance in the light-assisted hydrolytic dehydrogenation of ammonia borane
    (Elsevier, 2022) N/A; Department of Chemistry; Department of Chemistry; Aksoy, Merve; Korkut, Sibel Eken; Metin, Önder; PhD Student; Researcher; Faculty Member; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; 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 Sciences; College of Sciences; N/A; N/A; 46962
    Addressed herein is the enhancement of catalytic activity of Pt-based nanocatalysts in the hydrolysis of ammonia borane (AB) via in-situ synthesis of bimetallic AuPt alloy nanoparticles (NPs) supported on graphitic carbon nitride (gCN). The presented in-situ synthesis protocol yielded gCN/AuxPt100-x (x = 0, 8, 15, 33) nanocatalysts with highly dispersed AuxPt100-x NPs having the average particle sizes varied in the range of 1.6-2.6 nm over the gCN nanosheets. The generated gCN/Pt92Au8 (600.3 mol H-2 mol Pt-(1) min(-1)) and gCN/Pt85Au15 (587.1 mol H2 mol Pt-1 min(-1)) nanocatalysts showed higher catalytic activity compared to gCN/Pt-100 (525.7 mol H-2 mol Pt-1 min(-1)) under white-light irradiation, attributed to the synergistic effects aroused in the AuPt alloy NPs and heterojunctions formed between gCN and AuPt alloy NPs. The detailed characterization of photophysical properties of gCN/AuxPt100-x nanocatalysts revealed that their boosted catalytic activity is attributed to the improved charge kinetics, higher light absorption, and effective electron transfer channels from gCN to the bimetallic AuPt alloy NPs. The role of photogenerated carriers in the photocatalytic AB dehydrogenation was also elucidated via scavenger studies. This study shows that gCN/AuxPt100-x nanocatalysts can be prepared in situ during the hydrolysis of AB at room temperature and the yielded nanocatalysts have a significant role in boosting the hydrogen production from the light-assisted hydrolysis of AB.
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    Visible light-driven hydrogen evolution by using mesoporous carbon nitride-metal ferrite (MFe2O4/mpg-CN; M: Mn, Fe, Co and Ni) nanocomposites as catalysts
    (Pergamon-Elsevier Science Ltd, 2020) Yanalak, Gizem; Aslan, Emre; Patır, İmren Hatay; N/A; Department of Chemistry; Aksoy, Merve; Metin, Önder; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 46962
    Four different earth-abundant ferrite nanoparticles (MFe2O4, M: Mn, Fe, Co, Ni) with spinel structure were synthesized by using the surfactant-assisted high temperature thermal decomposition methods and then assembled on mesoporous graphitic carbon nitride (mpg-CN) to study their comparative catalysis for the photocatalytic hydrogen evolution reaction (HER) in the presence of Eosin-Y (EY) as a visible-light sensitizer. The yielded monodisperse ferrite nanoparticles and the MFe2O4/mpg-CN nanocomposites were characterized by using advanced analytical techniques including TEM, XPS, XRD, ICP-MS, and UVeVis DRS. All the tested MFe2O4/mpg-CN nanocomposites provided the better catalytic performance than that of pristine mpg-CN in the photocatalytic HER and their photocatalytic HER rates are in the order of NiFe2O4/mpg-CN > CoFe2O4/mpg-CN > MnFe2O4/mpg-CN > Fe3O4/mpg-CN > mpg-CN. Among the tested MFe2O4/mpg-CN nanocomposites, NiFe2O4/mpg-CN nanocomposite provided the highest hydrogen generation of 14.56 mmol g(-1), which is 6.75 times greater than that of pristine mpg-CN and, using EY as a visible light sensitizer and triethanolamine (TEOA) as a sacrificial reagent. According to the optical properties and energy band positions of the nanocomposites, a plausible mechanism for the NiFe2O4/mpg-CN catalyzed HER is proposed to give insights on the highest activity of NiFe2O4/mpg-CN nanocomposites among others. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Recent advances in the development of palladium nanocatalysts for sustainable organic transformations
    (Royal Soc Chemistry, 2021) Kılıç, Haydar; Nişancı, Bilal; N/A; Department of Chemistry; Aksoy, Merve; Metin, Önder; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 46962
    Synthetic organic transformations using large amount of hazardous raw materials, solvents, catalysts and energy as well as producing large amount of chemical waste are vital for the production of a large variety of pharmaceuticals, polymers, agrochemicals, intermediates, and fine chemical products. However, due to the increasing concern on the environmental problems and the obvious adverse effects of global warming in the world, all chemical industries using uneco-friendly organic transformations are required to make revolutionary changes in their manufacturing processes to make them greener and more sustainable. To develop organic transformation strategies possessing the objectives of sustainable and green chemistry, catalysis is a key technology. Palladium (Pd) has been a popular choice as a catalyst for various chemical reactions owing to its superior activity, selectivity and stability under different reaction conditions, but it is the second most expensive metal nowadays with a rapid increase in its price in last years. In this regard, the use of Pd nanocatalysts instead of unrecyclable homogeneous Pd complexes in the industrially important organic transformations is advantageous in terms of the development of more sustainable transformations. In this review, we highlight the Pd nanocatalysts that have been used in the development of sustainable organic transformations including transfer hydrogenation, C-H bond activation, and C-C coupling reactions (Sonogashira, Suzuki-Miyaura, and Mizoroki-Heck) in the last five years. We focused on examples outlining the principles of sustainable chemistry and a framework to describe greener organic transformations.