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    alpha-Thiophene end-capped styrene copolymer containing fullerene pendant moieties: Synthesis, characterization, and gas sensing properties
    (WILEY, 2016) Sennik, Erdem; Sennik, Busra; Alev, Onur; Kilinc, Necmettin; Yilmaz, Faruk; Ozturk, Zafer Ziya
    We report the synthesis, characterization, and gas sensing properties of a styrene copolymer bearing -thiophene end group and fullerene (C-60) pendant moieties P(S-co-CMS-C-60). First, the copolymer of styrene (S) and chloromethylstyrene (CMS) monomers was prepared in bulk via a bimolecular nitroxide-mediated radical polymerization (NMP) technique using benzoyl peroxide (BPO) as the radical initiator and nitroxy-functional thiophene compound (Thi-TEMPO) as the co-radical and this gave -thiophene end-capped copolymer P(S-co-CMS). The chloromethylstyrene units of P(S-co-CMS) allowed further side-chain functionalization onto P(S-co-CMS). The obtained P(S-co-CMS) was then reacted with sodium azide (NaN3) and this led to the copolymer with pendant azide groups, P(S-co-CMS-N-3), and then grafted with electron-acceptor C-60 via the reaction between N-3 and C-60. The final product was characterized by using NMR, FTIR, and UV-vis methods. Electrical characterization of P(S-co-CMS-C-60) thin film was also investigated at between 30 and 100 degrees C as the ramps of 10 degrees C. Temperature dependent electrical characterization results showed that P(S-co-CMS-C-60) thin film behaves like a semiconductor. Furthermore, P(S-co-CMS-C-60) was employed as the sensing layer to investigate triethylamine (TEA), hydrogen (H-2), acetone, and ethanol sensing properties at 100 degrees C. The results revealed that P(S-co-CMS-C-60) thin film has a sensing ability to H-2. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43641.
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    Electrical and VOC sensing properties of anatase and rutile TiO2 nanotubes
    (ELSEVIER SCIENCE SA, 2014) Sennik, Erdem; Kilinc, Necmettin; Ozturk, Zafer Ziya
    The dc electrical and volatile organic compound (VOC) sensing properties of TiO2 nanotubes in both anatase and rutile phases were investigated. TiO2 nanotube arrays were obtained in aqueous HF (0.5 wt.%) electrolytes by anodizing of Ti thin films that deposited on quartz substrates using thermal evaporation. Anodization was performed at 10 V in aqueous HF at 0 degrees C. Then the fabricated TiO2 nanotubes were annealed at 300 degrees C and at 700 degrees C under dry air for 5 h to obtain anatase and rutile phases, respectively. The TiO2 nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) as structural, and UV-vis spectrophotometer as optical. The current voltage characteristics of the nanotubes under dry air flow revealed that the conductivity of the sample with anatase phase was higher than that of the sample with rutile phase. The VOCs sensing properties of the nanotubes were investigated at 200 degrees C. It was found that the sensor response of anatase was higher than that of rutile for almost all VOC gases. On the other hand, the sensitivities of two sensors are the highest for isopropyl alcohol. (C) 2014 Elsevier B.V. All rights reserved.
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    Electrochemically growth of Pd doped ZnO nanorods on QCM for room temperature VOC sensors
    (ELSEVIER SCIENCE SA, 2016) Ozturk, Sadullah; Kosemen, Arif; Kosemen, Zuhal Alpaslan; Kilinc, Necmettin; Ozturk, Zafer Ziya; Penza, Michele
    Pristine and various palladium (Pd) doped ZnO nanorods have been synthesized on the quartz crystal microbalance (QCM) for volatile organic compound (VOCs) sensors at room temperature. The doping concentrations were varied from 0 mol% to 2.5 mol% by using electrochemical deposition method. The diameters of the fabricated nanorods were in the range of 100-200nm, and were increased with Pd doping. The tested VOCs included alcohols (ethanol, methanol, isopropyl), ester (ethyl acetate), aromatic (toluene, xylene), ketone (acetone) and chloroform in the different concentrations. The results indicated that the sensitivity of the sensing materials was enhanced with the increasing Pd doping concentrations except for the acetone and chloroform. The undoped ZnO nanorod sensor showed higher sensor response against to acetone and chloroform while exposing high concentration of two analytes due to the absorbing/adsorbing mechanism. All undoped and Pd doped nanorods sensors showed the highest sensitivity to xylene. (C) 2015 Elsevier B.V. All rights reserved.
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    Gas sensor application of hydrothermally growth TiO2 nanorods
    (ELSEVIER SCIENCE BV, 2015) Alev, Onur; Sennik, Erdem; Kilinc, Necmettin; Ozturk, Zafer Ziya; Urban, G; Wollenstein, J; Kieninger, J
    This study focuses on TiO2 nanorod-based gas sensor. TiO2 nanorods were fabricated on fluorine doped tin oxide (FTO) substrate by hydrothermal method. The hydrothermal solution was prepared with titanium but -oxide, hydrochloric acid and deionized water (volume ratio 1:30:30). The morphologies and structure of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Highly ordered and homogenous TiO2 nanorods obtained has a diameter of ca. 100 nm. Gas sensing properties of these structures were investigated against VOCs and different concentrations of H-2 at 200 degrees C. Sensor response was 200 (%) for 1000 ppm H-2. Among measured VOCs, TiO2 nanorods are only sensitive to isopropanol at 200 degrees C. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-ric-nd/4.0/) Peer-review under responsibility of the organizing committee of EUROSENSORS
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    Structural, electrical and H-2 sensing properties of copper oxide nanowires on glass substrate by anodization
    (ELSEVIER SCIENCE SA, 2016) Sisman, Orhan; Kilinc, Necmettin; Ozturk, Zafer Ziya
    Oxide (Cu2O) nanowires were synthesized on a glass substrate by using anodization method and then their structural, optical, electrical and gas sensing properties were investigated. Copper thin films that coated on glass substrates with evaporation technique were anodized in 0.2 M KOH + 0.1 M NH4F solution for 5 min at room temperature. Then, the crystallization of nanowires was handled via annealingat 280 degrees C under vacuum. The fabricated nanowires were characterized by scanning electron microscope(SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectrophotometer. The DC electrical measurements of Cu2O nanowires were done in the temperature range of 30 degrees C-200 degrees C under dry air. Cu2O nanowires were tested against to H-2 in dry air ambient depending on concentrationand temperature. It was observed that the ideal working temperature with highest sensor response was determined at 200 degrees C. (C) 2016 Elsevier B.V. All rights reserved.
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    The effect of Pd on the H-2 and VOC sensing properties of TiO2 nanorods
    (ELSEVIER SCIENCE SA, 2016) Sennik, Erdem; Alev, Onur; Ozturk, Zafer Ziya
    This work presents highly sensitive TiO2 nanorods modified with palladium to investigate the sensing properties of H-2 and volatile organic compound (VOC) gases. TiO2 nanorods were synthesized in a mixed solution containing 1 ml of titanium n-butoxide (TnBT) by the hydrothermal method. Pd on the surface of the TiO2 nanorods was decorated by heat treatment. The samples were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) techniques. The electrical properties of the TiO2 and Pd loaded TiO2 nanorods were investigated under a dry air flow at a temperature range from 30 degrees C to 200 degrees C. The H-2 sensing properties of the TiO2 nanorods decorated with Pd were investigated in the concentration range of 500-2000 ppm at 200 degrees C. Moreover, the effect of Pd on the VOC gas sensing properties of the TiO2 nanorods was examined at 200 degrees C. The results revealed that the nanorods modified with palladium exhibited excellent sensing performance to H-2 at 30 degrees C, and also had the appropriate sensor behavior at 200 degrees C with clear response-recovery, good stability, and reproducibility. The maximum VOC response was obtained for ethanol. (c) 2016 Published by Elsevier B.V.