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DEMİRCİ, SELİM

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DEMİRCİ

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Author: DEMİRCİ, SELİM × Subject: Photocatalytic activity ×

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Now showing 1 - 7 of 7
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    Photocatalytic activity of the thermally oxidized Zn-Ni-, Zn-Co-, Ni-Co-, and Zn-Ni-Co-coated alloy films
    (SPRINGER, 2021) DEMİRCİ, SELİM; Demirci, Selim; Dikici, Tuncay; Yurddaskal, Metin
    In this work, Zn-Ni-, Zn-Co-, Ni-Co-, and Zn-Ni-Co-coated alloy films were electrodeposited on titanium substrate. The coated alloy films were annealed in order to form oxides at 800 degrees C in air for 2 h. The crystalline structures, surface morphologies, and chemical composition of the samples were examined using X-ray diffraction techniques (XRD), scanning electron microscopy (SEM), and (EDX). Photocatalytic performance of samples was performed by means of the degradation of methylene blue (MB) under UV irradiation. The SEM results showed that the different morphologies such as needle-shaped nanowires, grains, and pores were formed on the surface. The results showed that the photocatalytic performance of the samples demonstrated differences according to alloy type. The Zn-Ni alloy coating exhibited better photocatalytic activity. Photocurrent measurements illustrated that Zn-Ni sample possessed the highest suppression of photogenerated charge carrier recombination and lowest charge transfer resistance (R-ct) layer. It is expected that this work could provide a promosing way for fabricating Zn-based photocatalyts in environmental redemediation.
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    The effects of growth conditions on the surface properties and photocatalytic activities of anatase TiO2 films prepared via electrochemical anodizing and annealing methods
    (SPRINGER, 2017) DEMİRCİ, SELİM; Dikici, Tuncay; Yurddaskal, Metin; Demirci, Selim; Celik, Erdal
    In the present work, nanostructured TiO2 films were prepared by electrochemical anodization process of titanium in fluoride-containing electrolytes using an innovative approach. After anodization, the TiO2 films were annealed at 480 degrees C for 2 h in air in order to acquire anatase phase transformation and increase its crystallinity. The effects of anodization voltage, electrolyte concentration and anodization time on the formation of TiO2 films and the photocatalytic degradation of methylene blue (MB) were discussed in details. The phase structure and surface morphology of the samples characterized by means of X-ray diffraction and scanning electron microscope. The as-prepared nanostructured TiO2 film anodized in 0.5% HF electrolyte at 15 V for 240 min showed excellent photocatalytic degradation of MB and is promising for environmental purification.
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    Synthesis and characterization of Ag doped TiO2 heterojunction films and their photocatalytic performances
    (ELSEVIER, 2016) DEMİRCİ, SELİM; Demirci, Selim; Dikici, Tuncay; Yurddaskal, Metin; Gultekin, Serdar; Toparli, Mustafa; Celik, Erdal
    In this study, undoped and silver (Ag) doped titanium dioxide (TiO2) films were successfully synthesized by sol-gel spin coating technique on the Si substrates. Photocatalytic activities of the TiO2 films with different Ag content were investigated for the degradation of methylene blue (MB) under UV light irradiation. The crystal phase structure, surface morphology, chemical and optical properties of Ag-doped TiO2 films were characterized using an X-ray diffractometer (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectrophotometer, and FTIR spectrophotometer. The results showed that the Ag-doped TiO2 films calcined at 500 degrees C had the crystalline anatase phases and the surface morphologies with some cracks. Ag substitution into TiO2 matrix enhanced the photocatalytic activity of TiO2 films under UV light irradiation as compared to the undoped TiO2 film. Furthermore, the results indicated that the 0.7% Ag doped TiO2 film exhibited a superior photocatalytic activity than that of undoped and other Ag-doped TiO2 films. This study demonstrated the potential of an application of Ag doped films to efficiently treat dissolved organic contaminants in water. (C) 2016 Elsevier B.V. All rights reserved.
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    Fabrication and characterization of novel iodine doped hollow and mesoporous hematite (Fe2O3) particles derived from sol-gel method and their photocatalytic performances
    (ELSEVIER SCIENCE BV, 2018) SARIOĞLU, CEVAT; Demirci, Selim; Yurddaskal, Metin; Dikici, Tuncay; Sanoglu, Cevat
    In this work, iodine (1) doped hollow and mesoporous Fe2O3 photocatalyst particles were fabricated for the first time through sol-gel method. Phase structure, surface morphology, particle size, specific surface area and optical band gap of the synthesized Fe2O3 photocatalysts were analyzed by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), BET surface analysis, particle size analyzer and UV-vis diffuse reflectance spectrum (UV-vis DRS), respectively. Also, electrochemical properties and photoluminescence spectra of Fe2O3 particles were measured. The results illustrated that high crystalline, hollow and mesoporous Fe2O3 particles were formed. The optical band gap values of the Fe203 photocatalysts changed between 2.104 and 1.93 eV. Photocatalytic efficiency of Fe2O3 photocatalysts were assessed via MB solution. The photocatalytic activity results exhibited that I doping enhanced the photocatalytic efficiency. 1% mole iodine doped (I-2) Fe2O3 photocatalyst had 97.723% photo degradation rate and 8.638 x 10(-2) min(-1) kinetic constant which showed the highest photocatalytic activity within 45 min. Moreover, stability and reusability experiments of Fe2O3 photocatalysts were carried out. The Fe2O3 photocatalysts showed outstanding stability after four sequence tests. As a result, I doped Fe2O3 is a good candidate for photocatalysts. (C) 2017 Elsevier B.V. All rights reserved.
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    Production of Zn-doped TiO2 film with enhanced photocatalytic activity
    (2022-12-01) DEMİRCİ, SELİM; DİKİCİ T., YILMAZ O., Akalin A., DEMİRCİ S., GÜLTEKİN S., YILDIRIM S., YURDDAŞKAL M.
    In this study, zinc (Zn)-doped titanium dioxide (TiO2) films were prepared using the two steps: anodic oxidation method and heat treatment process. The crystal structure, morphology and elemental composition of the Zn-doped TiO2 films were investigated. These films were characterized by scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicated that the TiO2 films with clear, uniform and short nanopores had a high surface area and high degree of crystallinity. The results showed that the asanodized TiO2 film was successfully obtained as anatase phase at 450 degrees C. The results of XPS analysis confirmed the presence of Zn in the lattice of TiO2 as dopant, and thermal diffusion technique was successfully done as doping method. The photocatalytic performances of the Zn-doped TiO2 films were evaluated in terms of their photodegradation rate of methylene blue (MB) in an aqueous solution under UV light irradiation. The results revealed that the Zn-doped TiO2 film had a higher photocatalytic activity in comparison with the undoped sample. This study inspired that Zn-doped TiO2 films are a great potential material to treat wastewater in industrial field.
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    Effect of heating rate on structure, morphology and photocatalytic properties of TiO2 particles: thermal kinetic and thermodynamic studies
    (SPRINGER, 2021) KIRAN YILDIRIM, BERÇEM; Dikici, Tuncay; Demirci, Selim; Tuncay, Mehmet Masum; Yildirim, Bercem Kiran; Kaya, Nusret
    In this study, TiO2 powders were produced via sol-gel route at 500 degrees C for 2 h with distinct heating rates. TGA-DTA, XRD, SEM, Raman spectroscopy, XPS, UV-vis spectroscopy and photoluminescence characterization techniques were carried out for TiO2 powders. Photocatalytic efficiency of TiO2 powders on degradation of methylene blue (MB) solution was examined in terms of different heating rates. Thermodynamic and non-isothermal kinetic study of TiO2 powders were estimated. TiO2 powders showed anatase phase based on XRD results. Surface morphology of TiO2 powders did not change with different heating rates. It can be concluded that heating rate played important role on band gap and photocatalytic activity. The band gap of the TiO2 particles decreased from 3.25 to 2.95 with increasing heating rate. The photocatalytic activity results exhibit that T1 powders have the highest photocatalytic performances. The kinetic constant and photocatalytic degradation rate were 0.00678 min(-1) and 83.48%, respectively. This could be attributed to high crystalline structure and low bulk vacancies or defects. Furthermore, TiO2 powders showed good stability. This study exhibited a new way to enhance the photocatalytic performances of pure TiO2 powders. [GRAPHICS]
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    PublicationOpen Access
    A study of heating rate effect on the photocatalytic performances of ZnO powders prepared by sol-gel route: Their kinetic and thermodynamic studies
    (ELSEVIER, 2020-03) TÜNÇAY, MEHMET MASUM; Demirci, Selim; Dikici, Tuncay; Tuncay, Mehmet Masum; Kaya, Nusret
    In this work, ZnO particles were fabricated by sol-gel method at different heating rate at 500 degrees C for 2 h. The ZnO powders were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy and photoluminescence, respectively. The effect of heating rate on photocatalytic activities of ZnO particles was evaluated by degradation of methylene blue (MB). The non-isothermal kinetics and thermodynamic properties were also estimated. The XRD results showed that ZnO had hexagonal wurtzite structure. The different heating rate didn't influence the surface morphology of ZnO powders. It was observed that the heating rate had a profound effect on reduction of band gap and photocatalytic performances. The band gap of the ZnO particles varied from 3.10 to 3.17. The ZnO sample prepared at 1 degrees C/min exhibited the highest photocatalytic activity. Its relative photocatalytic degradation rate and kinetic constant were 92.7% and 1.069x10(-2) min(-1), respectively. The results might be ascribed to low bulk vacancies, high surface oxygen vacancies and narrow band gap energy. Also, ZnO photocatalysts showed good stability after four sequence tests. This study provides a new strategy to improve the photocatalytic performances of ZnO photocatalyst for the degradation of organic contaminant.