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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 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 optical and device parameters of colloidal copper tungsten selenide ternary nanosheets(SPRINGER, 2018) Yildirim, Murat; Sarilmaz, Adem; Ozel, FarukHot injection synthesis route has been successfully applied for the preparation of high quality Cu2WSe4 (CWSe) nanosheets in order to determine their optical characterization and device parameters. Several techniques including XRD, SEM, TEM and SAED were used to characterize these nanosheets. These techniques confirmed that Cu2WSe4 nanosheets crystal shapes of synthesized are rectangular and square sheet and the average crystal size is between 20 and 40 nm. The spin coating technique was successfully used to deposit uniform of Cu2WSe4 thin film. Cu2WSe4 thin film has directly transition with a band gap of 1.64 eV. The dispersion of the refractive index is discussed in terms of the single oscillator Wemple-Didomenico (WD) model. The single oscillator energy and the dispersion energy were estimated. Au/Cu2WSe4/n-Si structures was fabricated and its main electrical characteristics described by using current-voltage (I-V) methods. The forward and reverse bias current voltage (I-V) characteristics of Au/Cu2WSe4/n-Si at room temperature were studied to investigate its basic electrical parameters [i.e. saturation current (), ideality factor (), barrier height (), series ()]. Structural and optical mechanisms were discussed for future applications in optoelectronic devices.Öğe Investigation of optical framework of chalcostibite nanocrystal thin films: An insight into refractive index dispersion, optical band gap and single-oscillator parameters(ELSEVIER SCIENCE SA, 2017) Yildirim, Murat; Aljabour, Abdalaziz; Sarilmaz, Adem; Ozel, FarukHerein, we report the synthesis of chalcostibite ( CuSbS2) nanocrystals based on hot injection method and the characterization of CuSbS2 thin films by spin coating technique. The deposited films were subjected to the UV-Vis spectrophotometer, XRD, TEM and SAED for optical, structural, morphological and elemental analysis. XRD pattern showed that CuSbS2 nanocrystals have chalcostibite structures and SAED diffraction spots supported the XRD results. Different optical parameters like extinction coefficient, refractive index, real and imaginary parts of dielectric constant and surface and volume energy loss functions have been calculated applying single term Sellmeier dispersion relation and Wemple eDiDomenico single oscillator model. The obtained results are discussed in detail. The optical dispersion and dielectric properties of the CuSbS2 have been determined by the transmittance and reflectance modes in the range of 300-1600 nm. Thus, the CuSbS2 is transparent up to 40-45% in the visible range. The optical bandgap determined by the optical absorbance spectrum analysis showed that thin films possess direct bandgap of 1.86 eV. The calculated refractive index of thin film varies between 1.76 and 2.11 throughout the spectral region considered. The results presented here permit a better understanding of the properties of the chalcostibite nanocrystals which in turn result in the design of more efficient solar cells. (C) 2017 Elsevier B. V. All rights reserved.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 Penternary chalcogenides nanocrystals as catalytic materials for efficient counter electrodes in dye-synthesized solar cells(NATURE PUBLISHING GROUP, 2016) Ozel, Faruk; Sarilmaz, Adem; Istanbullu, Bilal; Aljabour, Abdalaziz; Kus, Mahmut; Sonmezoglu, SavasThe penternary chalcogenides Cu2CoSn(SeS)(4) and Cu2ZnSn(SeS)(4) were successfully synthesized by hot-injection method, and employed as a catalytic materials for efficient counter electrodes in dye-synthesized solar cells (DSSCs). The structural, compositional, morphological and optical properties of these pentenary semiconductors were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive spectrometer (EDS) and ultraviolet-visible (UV-Vis) spectroscopy. The Cu2CoSn(SeS)(4) and Cu2ZnSn(SeS)(4) nanocrystals had a single crystalline, kesterite phase, adequate stoichiometric ratio, 18-25 nm particle sizes which are forming nanospheres, and band gap energy of 1.18 and 1.45 eV, respectively. Furthermore, the electrochemical impedance spectroscopy and cyclic voltammograms indicated that Cu2CoSn(SeS)(4) nanocrystals as counter electrodes exhibited better electrocatalytic activity for the reduction of iodine/iodide electrolyte than that of Cu2ZnSn(SeS)(4) nanocrystals and conventional platinum (Pt). The photovoltaic results demonstrated that DSSC with a Cu2CoSn(SeS)(4) nanocrystals-based counter electrode achieved the best efficiency of 6.47%, which is higher than the same photoanode employing a Cu2ZnSn(SeS)(4) nanocrystals (3.18%) and Pt (5.41%) counter electrodes. These promising results highlight the potential application of penternary chalcogen Cu2CoSn(SeS)(4) nanocrystals in low-cost, high-efficiency, Pt-free DSSCs.Öğe Photocatalytic H-2 evolution with a Cu2WS4 catalyst on a metal free D-pi-A organic dye-sensitized TiO2(ELSEVIER SCIENCE BV, 2017) Aslan, Emre; Gonce, Mehmet Kerem; Yigit, Mesude Zeliha; Sarilmaz, Adem; Stathatos, Elias; Ozel, Faruk; Can, MustafaA system comprising of a noble metal free Cu2WS4 catalyst and donor-pi-bridge-acceptor metal-free organic dyes (MZ-341 and MZ-235) sensitized TiO2 has been reported for the photocatalytic hydrogen production using triethanolamine (TEOA) as the sacrificial reagent under visible light irradiation. Cu2WS4 nanocubes were synthesized according to hot-injection reaction technique. The structural properties of the Cu2WS4 nanocubes were examined by microscopy (HR-TEM) and XRD techniques where the formation of nanocubes (rectangular and square cubes) with average edge length to be ranged from 100 to 500 nm and tetragonal phase (I-42m) was proved respectively. It was found that MZ-341 and MZ-235 dyes sensitized TiO2 have been produced 661 mol g 1 h(-1) and 531 mol g(-1) h(-1) hydrogen, respectively in TEOA solution at pH 9. When Cu2WS4, was used as a co-catalyst, hydrogen evolution by MZ-341 and MZ-235 sensitized TiO2 have been slightly increased to 1406 mol g(-1) h(-1) and 943 mol g(-1) h(-1), respectively. (C) 2017 Elsevier B.V. All rights reserved.Öğe 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.
