Yazar "Kilinc, Necmettin" seçeneğine göre listele
Listeleniyor 1 - 12 / 12
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe 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 ZiyaWe 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.Öğe Electrical and VOC sensing properties of anatase and rutile TiO2 nanotubes(ELSEVIER SCIENCE SA, 2014) Sennik, Erdem; Kilinc, Necmettin; Ozturk, Zafer ZiyaThe 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.Öğe Electrochemical Growth of Pd Doped ZnO Nanorods(ELECTROCHEMICAL SOC INC, 2015) Kosemen, Arif; Kosemen, Zuhal Alpaslan; Ozturk, Sadullah; Kilinc, Necmettin; San, Sait Eren; Tunc, Ali VeyselIn this work, dense arrays of pure and Pd doped zinc oxide (ZnO) nanorods (NRs) were fabricated by an electrochemical growth. Pure and Pd doped ZnO NRs were characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and optic spectroscopy. Structural studies confirmed that pure and doped ZnO NRs present the hexagonal wurtzite crystal structures. The optical properties of pure and doped ZnO NRs were found to present redshift by increasing doping concentration. The diameters of the NRs increase with increasing Pd doping concentration under same condition. Compared with pure ZnO NRs, the Pd doped ZnO NRs presents improved optical properties in terms of bandgap energy from 3.24 eV to 1.97 eV. These bandgap values were obtained by optical absorption using a UV-Visible spectrophotometer. In addition, Pd doping concentration in ZnO affects the active species on the surface such as oxygen deficiencies and hydroxyls. The electrochemically growing mechanism is also discussed in detail in the scope of this work. (C) 2015 The Electrochemical Society. All rights reserved.Öğe 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, MichelePristine 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.Öğe Fabrication of 1D ZnO nanostructures on MEMS cantilever for VOC sensor application(ELSEVIER SCIENCE SA, 2014) Kilinc, Necmettin; Cakmak, Onur; Kosemen, Arif; Ermek, Erhan; Ozturk, Sadullah; Yerli, Yusuf; Urey, HakanThis study reports the fabrication method and sensing performance for novel 1D zinc oxide (ZnO) nanorods and nanotubes grown on nickel MEMS cantilevers. The fabrication of the nanostructures and the cantilevers are simple and low-cost using standard lithography, electrodeposition, and hydrothermal etching processes. 1D ZnO nanostructures increase the total sensitive area for biological and chemical sensor applications. We performed experiments with various VOCs with a real-time sensor system developed in our laboratory. While Ni microcantilevers produced no signal, ZnO nanostructure coated microcantilevers showed good sensitivity and repeatable changes. Furthermore, the nanotube coated microcantilevers showed more than 10 fold increase in sensitivity compared to the nanorod coated microcantilevers which can be explained to the fact that ZnO nanotubes have higher surface area and subsurface oxygen vacancies and these provide a larger effective surface area with higher surface-to-volume ratio as compared to ZnO nanorods. The tests are performed using dynamic mode of operation near resonant frequency using magnetic actuation and optical sensing. The phase stability and the limit of detection of ZnO nanotube coated microcantilevers exposed to diethylamine (DEA) were 0.02 degrees and lower than 10 ppm, respectively. ZnO nanostructure coated microcantilevers have good potential for VOC sensor applications especially for amine groups. (C) 2014 Elsevier B.V. All rights reserved.Öğe 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, JThis 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 EUROSENSORSÖğe Hydrogen gas sensing using palladium-coated microdisk microresonators(SPIE-INT SOC OPTICAL ENGINEERING, 2015) Eryurek, Mustafa; Karadag, Yasin; Tasaltin, Nevin; Kilinc, Necmettin; Kiraz, Alper; Kudryashov, AV; Paxton, AH; Ilchenko, VS; Aschke, L; Washio, KAn SU-8 polymer microdisk resonator coated with a palladium (Pd) layer and coupled to a single-mode optical waveguide is used to as a hydrogen (H-2) gas sensor. In the presence of H2 a red shift is observed in the spectral positions of the microdisk whispering gallery modes (WGMs) due to the expansion in the Pd lattice. H-2 concentrations below the flammable limit (4%) down to 0.3% could be detected in nitrogen atmosphere at room temperature. For H-2 concentrations between 0.3 1%, WGM spectral positions shifted linearly with H-2 concentration at a rate of 32 pm/%H-2. Average response time of the devices was measured to be 50 s for 1% H-2. The proposed device concept can also be used to detect different chemical gases by using appropriate sensing layers.Öğe Optical sensor for hydrogen gas based on a palladium-coated polymer microresonator(ELSEVIER SCIENCE SA, 2015) Eryurek, Mustafa; Karadag, Yasin; Tasaltin, Nevin; Kilinc, Necmettin; Kiraz, AlperWe report an integrated optical sensor of hydrogen (H-2) gas employing an SU-8 polymer microdisk resonator coated with a palladium (Pd) layer and coupled to a single-mode optical waveguide. The sensing mechanism relies on the expansion in the Pd lattice due to palladium hydride formation in the presence of H-2. Strain induced in the microresonator then causes a red shift of the spectral positions of the resonator whispering gallery modes (WGMs) which is monitored using a tunable laser coupled to the waveguide. H-2 concentrations below the flammable limit (4%) down to 0.3% could be detected in nitrogen atmosphere at room temperature. For H-2 concentrations between 0.3 and 1%, WGM spectral positions shifted linearly with H-2 concentration at a rate of 32 pm/% H-2. Average response time of the devices was measured to be 50 s for 1% H-2. The proposed device concept can also be used to detect different chemical gases by using appropriate sensing layers. (C) 2015 Elsevier B.V. All rights reserved.Öğe Pd thin films on flexible substrate for hydrogen sensor(ELSEVIER SCIENCE SA, 2016) Ozturk, Sadullah; Kilinc, NecmettinIn this work, palladium (Pd) thin films were prepared via RF sputtering method with various thicknesses (6 nm, 20 nm and 60 nm) on both a flexible substrate and a hard substrate. Hydrogen (H-2) sensing properties of Pd films on flexible substrate have been investigated depending on temperatures (25-100 degrees C) and H-2 concentrations (600 ppm - 10%). The effect of H-2 on structural properties of the films was also studied. The films were characterized by Scanning Electron Microscopy (SEM) and X-ray diffraction. It is found that whole Pd films on hard substrate show permanent structural deformation after exposed to 10% H-2 for 30 min. But, this H-2 exposure does not causes any structural deformation for 6 nm Pd film on flexible substrate and 6 nm Pd film on flexible substrate shows reversible sensor response up to 10% H-2 concentration without any structural deformation. On the other hand, Pd film sensors that have the thicknesses 20 nm and 60 nm on flexible substrate are irreversible for higher H-2 concentration (>2%) with film deformation. The sensor response of 6 nm Pd film on flexible substrate increased with increasing H-2 concentration up 4% and then saturated. The sensitivity of the film decreased with increasing operation temperature. (C) 2016 Elsevier B.V. All rights reserved.Öğe Poly(3-Methylthiophene) Thin Films Deposited Electrochemically on QCMs for the Sensing of Volatile Organic Compounds(MDPI AG, 2016) Ozturk, Sadullah; Kosemen, Arif; Sen, Zafer; Kilinc, Necmettin; Harbeck, MikaPoly(3-methylthiophene) (PMeT) thin films were electrochemically deposited on quartz crystal microbalance QCM transducers to investigate their volatile organic compound (VOC) sensing properties depending on ambient conditions. Twelve different VOCs including alcohols, ketones, chlorinated compounds, amines, and the organosphosphate dimethyl methylphosphonate (DMMP) were used as analytes. The responses of the chemical sensors against DMMP were the highest among the tested analytes; thus, fabricated chemical sensors based on PMeT can be evaluated as potential candidates for selectively detecting DMMP. Generally, detection limits in the low ppm range could be achieved. The gas sensing measurements were recorded at various humid air conditions to investigate the effects of the humidity on the gas sensing properties. The sensing performance of the chemical sensors was slightly reduced in the presence of humidity in ambient conditions. While a decrease in sensitivity was observed for humidity levels up to 50% r.h., the sensitivity was nearly unaffected for higher humidity levels and a reliable detection of the VOCs and DMMP was possible with detection limits in the low ppm range.Öğe Sputtered platinum thin films for resistive hydrogen sensor application(ELSEVIER SCIENCE BV, 2016) Sennik, Erdem; Urdem, Seyma; Erkovan, Mustafa; Kilinc, NecmettinThis work presents hydrogen (H-2) sensing properties of platinum (Pt) thin film deposited on glass substrate by sputter technique. The Pt thin films with different thickness prepared using RF sputtering method were characterized by the XRD, SEM and XPS techniques. Temperature dependent resistances and the gas measurements of the Pt thin films 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 Pt thin film sensors were also examined in the concentration range of 0.1-1% H-2. The results revealed that the Pt thin film with 2 nm thickness exhibited the best sensing performance to H-2 at 30 degrees C under dry air flow. (C) 2016 Elsevier B.V. All rights reserved.Öğe 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 ZiyaOxide (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.
