Browsing by Author "Erdogan, Nursev"

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Citation - WoS: 10
Alkaline Hydrothermal Synthesis, Characterization, and Photocatalytic Activity of Tio₂ Nanostructures: the Effect of Initial Tio₂ Phase
(Amer Scientific Publishers, 2019) Erdogan, Nursev; Park, Jongee; Choi, Woohyuk; Kim, Soo Young; Ozturk, Abdullah; Metallurgical and Materials Engineering
One-dimensional (1D) titanate nanostructures were synthesized by hydrothermal route, using commercially available TiO2 (P25) and anatase powders as precursor materials and strong NaOH solution as catalyzer. The prepared titanates were calcined, followed by protonation to produce TiO2 nanostructures having enhanced photocatalytic and photovoltaic properties. The synthesized TiO2 1D nanostructures were characterized using field-emission scanning electron microscope, high-resolution electron microscope, X-ray diffraction analysis, and UV-Vis photospectroscopy to understand the effect of initial TiO2 phase on morphological and crystallographic features, and bandgap. Methylene blue degradation test was applied to evaluate the photoactivity of the products obtained after different stages of the process. The findings indicate that 1D TiO2 nanostructures form by different mechanisms from dissolved aggregates during hydrothermal process, depending on the crystal structure of the initial precursor used. Photocatalytic test results reveal that protonated titanates have considerable adsorption capability, while photocatalytic degradation depends on TiO2 transformation.
Citation - WoS: 28
Citation - Scopus: 27
Hydrothermal Synthesis of 3d Tio₂ Nanostructures Using Nitric Acid: Characterization and Evolution Mechanism
(Elsevier Sci Ltd, 2016) Erdogan, Nursev; Ozturk, Abdullah; Park, Jongee; Metallurgical and Materials Engineering
Various morphologies of TiO2 nanostructures were synthesized by HNO3 assisted hydrothermal treatment with respect to the acid molarity (1 M, 3 M, and 8 M), temperature (110, 140, and 180 degrees C), and time (1, 3, and 6 h). An additional sample was synthesized inside the protonated titanate nanoribbon coated vessel with the acid molarity of 8M at 140 degrees C for 3 h. The crystal structure and morphology of the nanostructures synthesized were investigated using X-Ray diffractometer, scanning electron microscope, and transmission electron microscope. The results revealed that lower acid concentrations, longer synthesis durations and higher temperatures favored anatase phase formation. Meanwhile, a phase pure 3D lotus structure ruffle TiO2 could be obtained by hydrothermal synthesis at 8M HNO3 concentration at 140 degrees C for 3 h using protonated Htitanate nanoribbons. A probable mechanism for the evolution of 3D ruffle lotus structure was highlighted. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Citation - WoS: 18
Citation - Scopus: 19
Synthesis and Enhanced Photocatalytic Activity of Molybdenum, Iron, and Nitrogen Triple-Doped Titania Nanopowders
(Elsevier Sci Ltd, 2016) Erdogan, Nursev; Park, Jongee; Ozturk, Abdullah; Metallurgical and Materials Engineering
A novel Mo, Fe, and N triple-doped rutile TiO2 nanopowder was synthesized with simple HNO3 assisted hydrothermal treatment. Powders synthesized were characterized by using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and Brunauer-Emmett-Teller (BET) surface area analysis techniques. Mo doping initiated the formation of a structure composed of a mixture of anatase and rutile with some modifications in morphology; but Mo, Fe, and N triple-doped titania powders are composed of entirely rutile structures. XPS analysis confirmed that Mo dissolved in the structure, replacing Ti atoms and forming some MoO3 partially crystallized nano regions on the surface. Existence of Fe in the TiO2 crystal lattice was confirmed by ICP analysis. Fe doping had an influence on the crystal structure and morphology. N was found to be dissolved in the co-doped structure by HNO3 catalyzer autogenously. Methylene blue degradation testing and band gap measurements were performed by using UV-vis photospectroscopy and diffuse reflector apparatus in order to evaluate the photocatalytic performance of the powders. Dopant elements decreased band gap energy steadily. An enhanced photoactivity was reached by Mo, Fe, and N triple-doping as compared with that of undoped, and mono doped TiO2 powders under UV-light irradiation. Possible reasons for the enhancement in photocatalytic activity are outlined. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Citation - WoS: 18
Citation - Scopus: 19
Synthesis and Enhanced Photocatalytic Activity of Nitrogen-Doped Triphasic Tio₂ Nanoparticles
(Elsevier Science Sa, 2019) Erdogan, Nursev; Bouziani, Asmae; Park, Jongee; Micusik, Matej; Kim, Soo Young; Majkova, Eva; Ozturk, Abdullah; Metallurgical and Materials Engineering
TiO2 nanoparticles of the single anatase phase, binary anatase-brookite phases, and ternary anatase-brookite-rutile phases were synthesized using an HNO3-catalyzed hydrothermal process. The types and amounts of phases varied depending on the hydrothermal synthesis conditions. The results revealed that N dissolves in different amounts and chemical states, depending on the phases present and their proportions in the nano particles. Brookite and rutile nanoparticles oriented through one direction were found to be crystallized by the surface transformation from anatase. Photocatalytic activity tests, evaluated by degradation of methylene blue (MB) under ultraviolet (UV) and visible light illumination, revealed that the N-doped TiO2 nanoparticles containing a ternary-phase mixture had the best photocatalytic activity. The MB degradation of the visible light-active nanoparticles was three times better than that of a commercially available well-known TiO2 powder, P25 under UV illumination. The enhanced photoactivity was attributed to the following: i) a high surface area, ii) suppression of the recombination of electron-hole pairs with ternary-phase mixture crystallized in heterojunctions, iii) larger anatase phase content, and iv) narrower band gap and facilitation of charge separation by dissolved N atoms.