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Öğe 1D Amorphous Tungsten-Based Ternary Refractory Metal Sulfides for Catalytic Hydrogen Evolution at Soft Interfaces(WILEY-V C H VERLAG GMBH, 2019) Aslan, Emre; Sarilmaz, Adem; Ozel, Faruk; Patir, Imren Hatay; Girault, Hubert H.Transition metals incorporated into molybdenum sulfide and tungsten sulfide matrixes are promising candidates for hydrogen evolution due to the unique chemical and physical properties. Here, we first describe a general strategy for the synthesis of rod-like ternary refractory metal sulfides (MWSx; M=Ni, Co, Fe and Mn) through a simple hot-injection method. The newly developed materials are affirmed as valuable alternatives to noble metal Pt due to their simple fabrication, inexpensive and impressive catalytic performance. We present that highly efficient catalysts for the hydrogen evolution at a polarized water/1,2-dichloroethane (DCE) interface by using the decamethylferrocene (DMFc). Kinetics of hydrogen evolution studies are monitored by two phase reactions using UV/Vis spectroscopy, and also further proved by gas chromatography. These ternary refractory metal sulfide catalysts show high catalytic activities on hydrogen evolution comparable to platinum. The rate of hydrogen evolution for the MWSx catalysts changed in the order Ni>Co>Fe>Mn according to the type of first row transition metals.Öğe Catalytic Hydrogen Evolution by Tungsten Disulfide at Liquid-Liquid Interfaces(WILEY-V C H VERLAG GMBH, 2014) Aslan, Emre; Patir, Imren Hatay; Ersoz, MustafaWS2, which is composed of cheap and earth-abundant elements, catalyzes the hydrogen-evolution reaction efficiently using the organic electron-donor decamethylferrocene. This catalytic activity has been investigated at liquid-liquid interfaces (water-1,2-dichloroethane) by voltammetry and biphasic reactions observed by UV/Vis spectroscopy and GC.Öğe Combined voltammetric and spectroscopic investigation of binding interaction between nifedipine and human serum albumin on polyelectrolyte modified ITO electrode(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Ozmen, Mustafa; Maltas, Esra; Patir, Imren Hatay; Bayrakci, MevlutThe binding interaction between the drug molecule, nifedipine (Nf), and the human serum albumin (HSA) on polyelectrolyte modified indium tin oxide (ITO) electrode has been investigated by the combination of electrochemical and fluorescence spectroscopy techniques. Surface modification has also been characterized by scanning electron microscopy (SEM) and Contact Angle (CA) measurements in each step. The cyclic voltammetry, electrochemical impedance parameters (peak potential difference (Delta E-p)), peak current difference (Delta I-p) and charge-transfer resistance (R-ct) indicate that nifedipine strongly interacted with human serum albumin molecule on the polyelectrolyte modified ITO electrode surface. Stern-Volmer quenching constant K-a is inversely correlated with the temperature, which indicates that the probable quenching mechanism of the nifedipine-human serum albumin binding reaction is initiated by complex formation. The results obtained from these techniques showed that Nf could bind to HSA. The binding constant (K-b) and the number of binding sites (n) of the drug with HSA at different temperatures were determined. At 298 K, K-b was found as 4.04 x 10(-3) and n was 1.08 for Nf-HSA. According to the van't Hoff equation, the thermodynamic parameters, Delta G, Delta H and Delta S, were obtained, showing the involvement of hydrophobic and electrostatic force in this interaction. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Cu Nanoparticles Electrodeposited at Liquid-Liquid Interfaces: A Highly Efficient Catalyst for the Hydrogen Evolution Reaction(WILEY-V C H VERLAG GMBH, 2015) Aslan, Emre; Patir, Imren Hatay; Ersoz, MustafaThe electrochemical deposition of Cu nanoparticles with an average diameter of approximately 25-35nm has been reported at liquid-liquid interfaces by using the organic-phase electron-donor decamethylferrocene (DMFc). The electrodeposited Cu nanoparticles display excellent catalytic activity for the hydrogen evolution reaction (HER); this is the first reported catalytic effect of Cu nanoparticles at liquid-liquid interfaces.Öğe Dye-Sensitized Cu2XSnS4 (X=Zn, Ni, Fe, Co, and Mn) Nanofibers for Efficient Photocatalytic Hydrogen Evolution(WILEY-V C H VERLAG GMBH, 2016) Gonce, Mehmet Kerem; Aslan, Emre; Ozel, Faruk; Patir, Imren HatayThe photocatalytic hydrogen evolution activities of low-cost and noble-metal-free Cu2XSnS4 (X=Zn, Ni, Fe, Co, and Mn) nanofiber catalysts have been investigated using triethanolamine as an electron donor and eosinY as a photosensitizer under visible-light irradiation. The rates of hydrogen evolution by Cu2XSnS4 (X=Zn, Ni, Fe, Co, and Mn) nanofibers have been compared with each other and with that of the noble metal Pt. The hydrogen evolution rates for the nanofibers change in the order Cu2NiSnS4>Cu2FeSnS4>Cu2CoSnS4>Cu2ZnSnS4>Cu2MnSnS4 (2028, 1870, 1926, 1420, and 389molg(-1)h(-1), respectively). The differences between the hydrogen evolution rates of the nanofibers could be attributed to their energy levels. Moreover, Cu2NiSnS4, Cu2FeSnS4, and Cu2CoSnS4 nanofibers show higher and more stable photocatalytic hydrogen production rates than that of the noble metal Pt under long-term irradiation with visible light.Öğe Earth-Abundant Cu2CoSnS4 Nanofibers for Highly Efficient H-2 Evolution at Soft Interfaces(WILEY-V C H VERLAG GMBH, 2015) Ozel, Faruk; Yar, Adem; Aslan, Emre; Arkan, Emre; Aljabour, Abdalaziz; Can, Mustafa; Patir, Imren HatayCu2CoSnS4 (CCTS) nanofibers have been fabricated by electrospinning and exhibit an excellent morphology with an average nanofiber diameter of 150 nm. Polyacrylonitrile (PAN) was used as templating polymer that leads to a decrease in imperfections in the crystalline nanofibers. CCTS and Cu2ZnSnS4 (CZTS) nanofibers, based on abundant and environmental friendly elements, efficiently enhanced the rates of biphasic proton reduction in the presence of an organic solubilized electron donor, decamethylferrocene (DMFc). This work paves the way for the exploration of copper-based chalcogenides as electrocatalysts for the hydrogen evolution reaction to replace noble metal Pt.Öğe An electrochemical biosensor based on human serum albumin/graphene oxide/3-aminopropyltriethoxysilane modified ITO electrode for the enantioselective discrimination of D- and L-tryptophan(ELSEVIER ADVANCED TECHNOLOGY, 2013) Zor, Erhan; Patir, Imren Hatay; Bingol, Haluk; Ersoz, MustafaA new electrochemical biosensor based on the human serum albumin/graphene oxide/3-aminopropyl-triethoxysilane modified indium tin oxide electrode (ITO/APTES/GO/HSA) has been developed for the discrimination of tryptophan (Trp) enantiomers. The electrode has been characterized by scanning electron microscopy (SEM) and electrochemical techniques. The electrochemical behaviors of the enantiomeric pairs (D- and L-Trp) at the ITO/APTES/GO/HSA electrode have been investigated by cyclic voltammetry in the concentration range of 0.10-1.0 mM. A clear separation between the oxidation peak potentials of D- and L-Trp, at 0.86 and 1.26 V, respectively, has suggested that the ITO/APTES/GO/HSA electrode can be used as an electrochemical biosensor for the discrimination of Trp enantiomers. In order to find the percentage of an enantiomeric form of tryptophan in a mixture, the ITO/APTES/GO/HSA electrode is used for the simultaneous detection of D- and L-Trp which showed that the percentage of one enantiomeric form can be easily measured in the presence of the other. (c) 2012 Elsevier B.V. All rights reserved.Öğe Enhanced Hydrogen Evolution Catalysis at the Liquid/Liquid Interface by NixSy and NixSy/Carbon Nanotube Catalysts(WILEY-V C H VERLAG GMBH, 2017) Akin, Ilker; Aslan, Emre; Patir, Imren HatayNixSy (NiS and Ni17S18) nanoparticles and their nano-composite with carbon nanotubes (NixSy/CNT) were synthesized by a modified hydrothermal method and characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray microanalysis. The synthesized materials were used as hydrogen evolution catalysts at the water/1,2-dichloroethane interface by using decamethylferrocene as a lipophilic electron donor. The hydrogen evolution reaction in biphasic systems was investigated by two-phase reactions and by cyclic voltammetry with a four-electrode system. A kinetic study of the hydrogen production was also performed. The rates of the reactions catalyzed by the NixSy nanoparticles and the NixSy/CNT nanocomposite were found to be about 690-fold and 2000-fold higher, respectively, than the rate for the reaction performed in the absence of a catalyst.Öğe Enhanced Hydrogen Evolution Catalysis Based on Cu Nanoparticles Deposited on Carbon Nanotubes at the Liquid/Liquid Interface(WILEY-V C H VERLAG GMBH, 2016) Aslan, Emre; Akin, Ilker; Patir, Imren HatayCopper nanoparticles were electrodeposited in situ on a conductive multi-walled carbon nanotubes (MWCNT) support at a free-standing water/1,2-dichloroethane interface. The Cu/MWCNT nanocomposites act as highly active hydrogen evolution catalysts at the interface in the presence of lipophilic decamethylferrocene as the reducing agent.Öğe Fluorinated-cobalt phthalocyanine catalyzed oxygen reduction at liquid/liquid interfaces(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Patir, Imren HatayCobalt fluoro-phthalocyanine (CoFPc) can efficiently catalyze the reduction of oxygen (O-2) by a weak electron donor, namely tetrathiafulvalene (TIT), at the polarized water/1,2-dichloroethane (DCE) interface. Two-phase shake flask experiments and ion transfer voltammetry results suggest that the catalytic reaction proceeds as a proton-coupled electron transfer reduction of oxygen to mainly hydrogen peroxide, where a proton transfer from water to DCE is occurring concomitantly with the electron transfer reaction between TTF and oxygen. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Highly Active Cobalt Sulfide/Carbon Nanotube Catalyst for Hydrogen Evolution at Soft Interfaces(WILEY-V C H VERLAG GMBH, 2016) Aslan, Emre; Akin, Ilker; Patir, Imren HatayHydrogen evolution at polarized liquid-liquid interfaces [water/1,2-dichloroethane (DCE)] by the electron donor decamethylferrocene (DMFc) is catalyzed efficiently by the fabricated cobalt sulfide (CoS) nanoparticles and nanocomposites of CoS nanoparticles formed on multi-walled carbon nanotubes (CoS/CNT). The suspended CoS/CNT nanocomposite catalysts at the interface show a higher catalytic activity for the hydrogen evolution reaction (HER) than the CoS nanoparticles due to the high dispersity and conductivity of the CNT materials, which can serve as the main charge transport pathways for the injection of electrons to attain the catalytic sites of the nanoparticles. The reaction rate increased more than 1000-fold and 300-fold by using CoS/CNT and CoS catalysts, respectively, when compared to a non-catalyzed reaction.Öğe Hydrogen Evolution Catalyzed by Cu2WS4 at Liquid-Liquid Interfaces(AMER CHEMICAL SOC, 2016) Ozel, Faruk; Aslan, Emre; Sarilmaz, Adem; Patir, Imren HatayThe present study reports, for the first time, both a facile synthesis for ternary Cu2WS4 nanocubes, which were synthesized by a simple and low-cost hot-injection method, and the hydrogen evolution reaction at a biomembrane-like polarized water/1,2-dichloroethane interface catalyzed by Cu2WS4 nanocubes. The rate of hydrogen evolution reaction is increased by about 1000 times by using Cu2WS4 nanocubes when compared to an uncatalyzed reaction.Öğe Investigation of structural, optical and dielectrical properties of Cu2WS4 thin film(SPRINGER, 2017) Yildirim, Murat; Ozel, Faruk; Sarilmaz, Adem; Aljabour, Abdalaziz; Patir, Imren HatayTernary I-Cu2WS4 were synthesized based on hot-injection process and their thin films are prepared by spin coating techniques at ambient temperature. The energy dispersive analysis of X-rays of the thin films confirmed that synthesized thin film is stoichiometric. Transmittance and reflectance have been used to determine the optical, dispersion and dielectric properties of the Cu2WS4 in the range of 200-2400 nm. The transparency of the Cu2WS4 is 40-45% in the visible range. Optical dispersion parameters have been calculated by using the single term Sellmeier dispersion relation and Wemple-DiDomenico single oscillator model. Several dispersion parameters were determined by the analysis of refractive index dispersion.Absorption coefficient (alpha), extinction coefficient (), the Urbach energy (), real and imaginary parts of dielectric constant (epsilon) and surface and volume energy loss function have been calculated. The optical bandgap determined by the optical absorbance spectrum analysis showed that thin films possess a direct bandgap of 1.74 eV.Öğe Photocatalytic hydrogen evolution based on Cu2ZnSnS4, Cu2NiSnS4 and Cu2CoSnS4 nanocrystals(ELSEVIER SCIENCE BV, 2016) Ozel, Faruk; Aslan, Emre; Istanbullu, Bilal; Akay, Ozge; Patir, Imren HatayA low cost and environment-friendly Cu2ZnSnS4, Cu2CoSnS4 and Cu2NiSnS4 nanocrystals have been used as a catalyst instead of noble metal Pt for the photocatalytic hydrogen evolution in the presence of triethanolamine and eosin Y as a sacrificial reducing agent and a photosensitizer, respectively under visible light irradiation. Cu2NiSnS4 and Cu2CoSnS4 nanocrystals exhibit a longer photostability and a higher hydrogen evolution rate of 1200 mu molg(-1) h(-1), 900 mu molg(-1) h(-1), respectively, compared to that of Cu2ZnSnS4 by producing hydrogen 670 mu molg(-1) h(-1). (C) 2016 Elsevier B.V. All rights reserved.Öğe Photocatalytic hydrogen evolution based on Cu2ZnSnS4, Cu2ZnSnSe4 and Cu2ZnSnSe4-xSx nanofibers(ROYAL SOC CHEMISTRY, 2015) Gonce, Mehmet K.; Dogru, Melike; Aslan, Emre; Ozel, Faruk; Patir, Imren Hatay; Kus, Mahmut; Ersoz, MustafaNew photocatalytic systems for hydrogen evolution from water have been reported by using low cost and environmentally-friendly Cu-2-ZnSnS4, Cu2ZnSnSe4, and Cu2ZnSnSe4-xSx nanofiber catalysts in the presence of eosin Y as a photosensitizer and a sacrificial reducing agent triethanolamine under visible light irradiation. The rate of hydrogen evolution with Cu2ZnSnS4 is greater than those with Cu(2)znSnSe(4) and Cu2ZnSnSe4-xSx, producing hydrogen at 1428 mu mol g(-1) h(-1), 833 mu mol g (1) h(1) and 739 mmol g(1) h(1), respectively.Öğe Photocatalytic Hydrogen Evolution by Oleic Acid-Capped CdS, CdSe, and CdS0.75Se0.25 Alloy Nanocrystals(WILEY-V C H VERLAG GMBH, 2014) Aslan, Emre; Birinci, Okan; Aljabour, Abdalaziz; Ozel, Faruk; Akin, Ilker; Patir, Imren Hatay; Kus, MahmutPhotocatalytic generation of hydrogen by using oleic acid-capped CdS, CdSe, and CdS0.75Se0.25 alloy nanocrystals (quantum dots) has been investigated under visible-light irradiation by employing Na2S and Na2SO3 as hole scavengers. Highly photostable CdS0.75Se0.25 alloy nanocrystals gave the highest hydrogen evolution rate (1466 mu molh(-1) g(-1)), which was about three times higher than that of CdS and seven times higher than that of CdSe.Öğe Photoinduced Biphasic Hydrogen Evolution: Decamethylosmocene as a Light-Driven Electron Donor(WILEY-V C H VERLAG GMBH, 2013) Ge, Peiyu; Olaya, Astrid J.; Scanlon, Micheal D.; Patir, Imren Hatay; Vrubel, Heron; Girault, Hubert H.Excitation of the weak electron donor decamethylosmocene on illumination with white light produces an excited-state species capable of reducing organically solubilized protons under biphasic conditions. Insight into the mechanism and kinetics of light-driven biphasic hydrogen evolution are obtained by analysis with gas chromatography, cyclic voltammetry, and UV/Vis and H-1 NMR spectroscopy. Formation of decamethylosmocenium hydride, which occurs prior to hydrogen evolution, is a rapid step relative to hydrogen release and takes place independently of light activation. Remarkably, hydride formation occurs with greater efficiency (ca. 90% conversion) under biphasic conditions than when the reaction is carried out in an acidified single organic phase (ca. 20% conversion). Cyclic voltammetry studies reveal that decamethylosmocene has a higher proton affinity than either decamethylferrocene or osmocene.Öğe A systematic comparative study of the efficient co-catalyst-free photocatalytic hydrogen evolution by transition metal oxide nanofibers(PERGAMON-ELSEVIER SCIENCE LTD, 2018) Yanalak, Gizem; Aijabour, Abdalaziz; Aslan, Emre; Ozel, Faruk; Patir, Imren HatayThe efficiencies of a series of hydrogen evolving catalysts based on metal oxide nanofibers (NiO, Co3O4, Mn3O4) are investigated for the photocatalytic hydrogen evolution from water without using any co-catalyst under the visible light irradiation by using triethanolamine (TEOA) as an electron donor and Eosin-Y (EY) dye as a photosensitizer. It is found that the photocatalytic hydrogen evolution activities follow the order as: Mn3O4Öğe Ternary copper-tungsten-disulfide nanocube inks as catalyst for highly efficient dye-sensitized solar cells(PERGAMON-ELSEVIER SCIENCE LTD, 2018) Gulen, Mahir; Sarilmaz, Adem; Patir, Imren Hatay; Ozel, Faruk; Sonmezoglu, SavasIn this report, ternary copper-tungsten-disulfide (Cu2WS4) nanocube inks are successfully synthesized via colloidal synthesis process, utilizing metal chloride as cation sources, sulphur powder combined with oleylamine as coordinating solvent and ligand, and employed, for the first time, as catalyst for counter electrode (CE) to build up a low-cost/high-efficient dye-sensitized solar cell (DSSC). The composition, structure and morphology of these nanocubes are characterized by performing pertinent analyses. The experimental results indicate that the nanocubes are single phase, nearly stoichiometric composition and a mean size of 200 nm. From outstanding electrochemical performance, Cu2WS4 CE exhibits excellent catalytic activity towards iodine redox couples in the electrolyte and fast electron-transfer at the interfaces of CE/electrolyte owing to its larger surface area, more conductive network, lower charge transfer resistance and strong adherence of CWS nanocubes on substrate compare to Pt. The CWS-based cell displays a higher power conversion efficiency of 8.94% than that with Pt CE (8.00%), as well as an excellent reversibility/durability with long-term stability. The newly developed material confirms as valuable alternatives to Pt-free CEs for reduction in DSSCs and is of peculiar interest because of its low-cost, high stability simple fabrication process and impressive photovoltaic performance. (C) 2018 Elsevier Ltd. All rights reserved.
