Researcher:
Küçükkeçeci, Hüseyin

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Hüseyin

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Küçükkeçeci

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Küçükkeçeci, Hüseyin

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2020 - 20229

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Now showing 1 - 9 of 9
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    A NIR-light-driven black phosphorus based nanocomposite for combating bacteria
    (Wiley-V C H Verlag Gmbh, 2022) Çekçekoğlu, İlknur Aksoy; Sevgi, Fatih; Ersöz, Mustafa; Patır, İmren Hatay; Department of Chemistry; N/A; Department of Chemistry; Eroğlu, Zafer; Küçükkeçeci, Hüseyin; Metin, Önder; Researcher; Researcher; Faculty Member; Department of Chemistry; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 46962
    Nanocomposites of semiconducting two-dimensional (2D) materials provide advantageous for combating bacterial infections to overcome antibiotic resistance. In this study, the nanocomposites of 2D black phoshorus (BP) and silver nanoparticles (NPs) were prepared by anchoring as-synthesized Ag NPs on few-layer BP nanosheets via liquid self-assembly method and used as a NIR-light-driven antibacterial agent against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and Gram-positive bacteria (Enterococcus faecalis and Bacillus cereus). The BP/Ag nanocomposites showed excellent photothermal effect and oxidative stress ability to inhibit the initial logarithmic growth phase of E. faecalis and B. cereus. According to the bacterial growth curve, agar plate assay and live/dead viability test, as-synthesized BP/Ag nanocomposites were found to be more effective antibacterial agent for Gram-positive bacteria than Gram-negative bacteria. The presented NIR-light-driven BP-based nanoplatform can open a new avenue for avoiding bacterial resistance and combating pathogenic bacteria and also broad-spectrum disinfection applications.
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    Mesoporous graphitic carbon nitride/black phosphorus/agpd alloy nanoparticles ternary nanocomposite: a highly efficient catalyst for the methanolysis of ammonia borane
    (Amer Chemical Soc, 2020) N/A; Department of Chemistry; N/A; Department of Chemistry; Korkut, Sibel Eken; Küçükkeçeci, Hüseyin; Metin, Önder; Researcher; Researcher; Faculty Member; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 46962
    A novel ternary nanocomposite, mesoporous graphitic carbon nitride/black phosphorus-AgPd (denoted mpg-CN/BP-AgPd), was successfully fabricated by assembling the as -prepared AgPd alloy nanoparticles (NPs) on mesoporous graphitic carbon nitride/black phosphorus (mpg-CN/BP) binary composites. This novel nanocomposite comprises a heterojunction support material formed by two distinct nonmetallic semiconductors (mpg-CN and BP) with adaptable band gaps and edge voltages, providing enhanced catalytic activity to AgPd alloy NPs in hydrogen generation from the methanolysis of ammonia borane (AB) compared to its single components under the blue light-emitting diode (LED) light illumination. The yielded mpg-CN/BP-AgPd ternary nanocomposites were characterized by many advanced analytical techniques (transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL), time-resolved spectroscopy, inductively coupled plasma-mass spectroscopy (ICP-MS), and fourier transform infrared (FTIR), and then they were tested as catalysts in hydrogen generation from the methanolysis of AB at room temperature. Several parameters such as the effect of mpg-CN/BP ratio, alloy composition, and type of the light source were studied to optimize the catalytic activity of the mpg-CN/BP-AgPd nanocomposites in the methanolysis of AB. The best catalytic activity of mpg-CN/BP-AgPd nanocomposites was obtained using an mpg-CN/BP ratio of 5/1 (wt/wt) and Ag50Pd50 alloy composition under the blue LED illumination at room temperature. The activity of the ternary nanocomposites was further enhanced by the acetic acid treatment, and a high initial turnover frequency of 43.7 mol(center dot H-2) mol(catalyst)(-1) min(-1) was reported. Besides their high catalytic activity, the mpg-CN/BP-AgPd nanocomposites were reusable catalysts in the methanolysis of AB. This study also included detailed kinetics of AB methanolysis catalyzed by mpg-CN/BP-AgPd nanocomposites.
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    Black phosphorus as a metal-free, visible-light-active heterogeneous photoredox catalyst for the direct C-H arylation of heteroarenes
    (Royal Society of Chemistry (RSC), 2020) Kılıç, Haydar; Department of Chemistry; N/A; Department of Chemistry; Kalay, Erbay; Küçükkeçeci, Hüseyin; Metin, Önder; Researcher; Master Student; Faculty Member; Department of Chemistry; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; 59456; N/A; 46962
    Black phosphorus (BP) is for the first time employed as a metal-free, heterogeneous photoredox catalyst for the direct C-H arylation of heteroarenes with aryl diazonium salts. The arylated heteroarenes are obtained in moderate to good yields under visible-light illumination, and the protocol is shown to be applicable for the scale-up synthesis.
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    Ag/AgCl clusters derived from AgCu alloy nanoparticles as electrocatalysts for the oxygen reduction reaction
    (Royal Society of Chemistry (RSC), 2022) Harfouche, Messaoud; N/A; N/A; N/A; Department of Chemistry; Department of Chemistry; Balkan, Timuçin; Küçükkeçeci, Hüseyin; Aksoy, Dilan; Metin, Önder; Kaya, Sarp; Other; Master Student; PhD Student; Faculty Member; Faculty Member; Department of Chemistry; 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); N/A; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; N/A; 46962; 116541
    The structural changes induced by the selective dealloying of bimetallic alloy electrocatalysts could have a significant impact on the kinetics of the oxygen reduction reaction (ORR). Herein, we show that the activity of bimetallic AgCu alloy nanoparticles (NPs) towards the ORR can be enhanced by dealloying Cu in an acidic medium. A combination of core-level X-ray spectroscopy and X-ray diffraction investigations with scanning electron microscopy reveals that dealloying in HCl performed on annealed AgCu alloy NPs leads to the formation of relatively large nanostructures composed of Ag/AgCl. The initial composition of AgCu alloy NPs and the extent of the AgCl formation on Ag surfaces have a significant effect on the ORR activity. Furthermore, the formation of the active surface structure strongly depends on the initial composition of alloy NPs. Ag decorated with AgCl formed after dealloying Ag7Cu3 alloy NPs presents a superb ORR activity with a high onset potential (E-0) of approximate to 0.97 V vs. RHE, comparable to commercial Pt/C catalysts and outperforms dealloyed Ag3Cu2 and pristine Ag electrocatalysts. We suggest that Ag+ stabilized in the presence of sub-stoichiometric Cl- plays a critical role in the superior activity of the catalyst.
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    One -pot synthesis of monodisperse copper -silver alloy nanoparticles and their composition -dependent electrocatalytic activity for oxygen reduction reaction
    (Elsevier Science Sa, 2020) N/A; N/A; Department of Chemistry; Department of Chemistry; Department of Chemistry; Balkan, Timuçin; Küçükkeçeci, Hüseyin; Zarenezhad, Hamaneh; Kaya, Sarp; Metin, Önder; Other; Researcher; Researcher; Faculty Member; Faculty Member; Department of Chemistry; 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); N/A; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; College of Sciences; N/A; N/A; N/A; 116541; 46962
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    Ternary nanocomposites of mesoporous graphitic carbon nitride/black phosphorus/gold nanoparticles (mpg-CN/BP-Au) for photocatalytic hydrogen evolution and electrochemical sensing of paracetamol
    (Elsevier, 2021) Yanalak, Gizem; Doganay, Fatmanur; Aslan, Emre; Ozmen, Mustafa; Bas, Salih Zeki; Patir, Imren Hatay; Department of Chemistry; Department of Chemistry; Department of Chemistry; Eroğlu, Zafer; Küçükkeçeci, Hüseyin; Metin, Önder; Researcher; Researcher; Faculty Member; Department of Chemistry; College of Sciences; College of Sciences; College of Sciences; N/A; N/A; 46962
    We report herein the fabrication of a novel ternary nanocomposite of mesoporous graphitic carbon nitride/black phosphorus-gold nanoparticles (mpg-CN/BP-Au) and its catalytic performance in the photocatalytic hydrogen evolution reaction (HER) and electrochemical detection of paracetamol. The photocatalytic hydrogen production rate of mpg-CN/BP-Au nanocomposite (1024 mu mol g-1 for 8 h) is compared with mpg-CN, mpg-CN/BP and mpgCN/Au in the presence of triethanolamine (TEOA) as a hole scavenger under the visible light. In addition to the photocatalytic HER application, as-prepared mpg-CN/BP-Au nanocomposite was deposited on modified glassy carbon electrode (mpg-CN/BP-Au/GCE) and for the first time tested for the detection of paracetamol (PA). Under the optimum conditions, linear range of paracetamol detection was found to be in the range of 0.3-120 mu M with a detection limit of 0.0425 mu M. mpg-CN/BP-Au/GCE provided higher electrocatalytic activity than pristine mpgCN and all other tested binary nanocomposites. The enhanced photo- and electrochemical activity of mpgCN/BP-Au/GCE are attributed to formation of heterojunction between BP and mpg-CN materials. Additionally, Au nanoparticles increase the rate of adsorption of mpg-CN/BP due to the excellent electrical properties and spillover effect. We believe that the presented design and catalysis of the ternary nanocomposite will pave a way in many photo- and electrochemical applications.
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    One-pot synthesis of monodisperse copper-silver alloy nanoparticles and their composition-dependent electrocatalytic activity for oxygen reduction reaction
    (Elsevier B.V., 2020) N/A; N/A; Department of Chemistry; Department of Chemistry; Department of Chemistry; Balkan, Timuçin; Küçükkeçeci, Hüseyin; Zarenezhad, Hamaneh; Kaya, Sarp; Metin, Önder; Other; Researcher; Researcher; Faculty Member; Faculty Member; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; N/A; N/A; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); N/A; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; College of Sciences; N/A; N/A; N/A; 116541; 46962
    Development of an economical, well-defined and efficient electrocatalyst having a potential to replace Pt/C is crucial for oxygen reduction reaction (ORR). In this respect, we report herein one-pot wet-chemical protocol for the composition-controlled synthesis of monodisperse CuAg alloy nanoparticles (NPs) and their composition-dependent electrocatalytic activities in ORR for the first time under an alkaline condition. The presented synthetic procedure yields CuAg NPs that exhibit monodisperse size distribution with an average particle diameter of ∼8 nm. Almost homogenous CuAg alloy formation is proved by using many advanced analytical techniques despite the considerable lattice mismatch between Cu and Ag. At all compositions investigated, the ORR activities of CuAg electrocatalysts are found to be significantly higher than monometallic Ag NPs. Improved ORR kinetics of CuAg alloy NPs are demonstrated by Tafel slopes (85 mV/dec for Cu30Ag70, 84 mV/dec for Cu40Ag60 and 78 mV/dec for Cu60Ag40 which are all smaller than that of monometallic Ag (113 mV/dec). Electrochemical impedance measurements support these findings and represent that charge transfer resistance strongly depends on composition of CuAg electrocatalyst. The ORR activity and surface analysis results put Cu40Ag60 forward since Cu oxidation is suppressed in Cu40Ag60 NPs, caused by Ag enhancement in the surface. © 2020 Elsevier B.V.
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    Black phosphorus-based photocatalysts for energy and environmental applications
    (Elsevier, 2021) Department of Chemistry; N/A; N/A; Department of Physics; Metin, Önder; Küçükkeçeci, Hüseyin; Eroğlu, Zafer; Altan, Orhan; Faculty Member; Researcher; Researcher; Other; Department of Chemistry; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; N/A; College of Sciences; 46962; N/A; N/A; N/A
    Photocatalysis using semiconductor materials to conduct chemical reactions more efficiently with the aid of sunlight irradiation is foreseen as a promising solution to combat the energy and environmental pollution crisis that the world is facing at present. Finding a suitable semiconductor material that harvests a large portion of the sunlight spectrum with high photocatalytic efficiency lies in the heart of photocatalysis. In this regard, black phosphorus (BP), a rising star two-dimensional (2D) semiconducting material, has recently been regarded as an abundant, nontoxic, metal-free, and cheap photocatalyst with a suitable bandgap and broad light absorption ability. In this chapter, after the introduction of the general properties and synthesis of BP, the photocatalytic efficiency of BP and BP-based composites in energy and environmental applications are summarized.
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    Photothermal antibacterial and antibiofilm activity of black phosphorus/gold nanocomposites against pathogenic bacteria
    (Amer Chemical Soc, 2020) Aksoy, Ilknur; Sevgi, Fatih; Patir, Imren Hatay; N/A; Department of Chemistry; Küçükkeçeci, Hüseyin; Metin, Önder; Master Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 46962
    Black phosphorus (BP) as a layered two-dimensional (2D) semiconductor material with a tunable band gap has attracted growing attention for promising applications in diverse fields including biotechnology owing to its excellent physical and chemical properties. In this study, BP crystals were synthesized using a chemical vapor transport method and exfoliated into BP nanosheets in deoxygenated water or hexane. Next, monodisperse Au nanoparticles that were synthesized using a surfactant-assisted chemical reduction method were assembled on exfoliated BP nanosheets hexane to yield BP/Au nanocomposites. The photothermal antibacterial and antibiofilm activities of BP nanosheets and BP/Au nanocomposites were investigated against Enterococcus faecalis, a pathogenic biofilm-forming bacterium, by studying the photothermal effect and bacterial growth curve and using colony counting and live/dead fluorescence staining methods under near-infrared (NIR) light irradiation. Thanks to the higher photothermal conversion efficiency of BP/Au nanocomposites than that of bare BP nanosheets under NIR light irradiation, they destructed the bacterial cell membrane more efficiently than bare BP with the biofilm inhibition rate of 58%. It should be noted that this is the first study on the antibacterial and antibiofilm activity of BP/Au nanocomposites via a photothermal process under NIR light irradiation. This work shows the potential of BP/Au nanocomposites in fighting against pathogenic bacteria and paves the way for the exploration of antibacterial platforms based on the biocompatible 2D semiconductor BP.