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In this study, titanium dioxide (TiO2) nanostructures were produced on pure titanium in different electrolytes at constant voltage of 20 V for 30 min. The crystallographic structure, surface morphology, and optical properties of the films were investigated by XRD, SEM, and UV-vis spectrum, respectively. The wettability of the samples was determined by contact angle measurement equipment. The photocatalytic properties of the TiO2 films were tested by the degradation of a methylene blue (MB) as the model reaction under UV light irradiation. The results showed that the electrolyte composition can play an important role in the surface morphology of nanostructured TiO2 films and therefore on various properties such as optics, electronics, sensing, and degradation. The SEM images of the samples demonstrated that surface morphology was directly affected by the electrolyte composition. It is known that the surface area is a dominant factor affecting the photocatalytic activity of a porous TiO2 layer prepared by anodic oxidation. The TiO2 film (sample C) anodized in 1 M Na2SO4 containing 5 wt.% NH4F exhibited better photocatalytic performance as compared to the other oxide films. This is because a higher surface area with dense pore structure favors more photocatalytic active areas. The photocatalytic degradation efficiency of MB using sample C was reached to 92.35% and rate constant 5.92 x 10(-3), respectively. Moreover, this sample showed lowest band gap energy that was almost 3.167 eV. We believe that new anodic TiO2 nanoporous structures are highly promising in photocatalytic decomposition of water and pollutants elimination.

This work aimed to comprehensively assess the influence of various surface modifications on the formation of apatite ability for EBM Ti-6Al-4V alloy. Sandblasting (S), acid-etching (E), sandblasting and acid-etching (SE), anodization (NA), micro-arc oxidations in 1M H2SO4solution (SM) and 1M H3PO4solution (PM) methods were applied to modify electron beam melted (EBM) Ti-6Al-4V surface. The α/α’-Ti structures and TiO2phases were detected by XRD. The surface roughness (Ra) values ranged from 0.25 μm and 2.86 μm. The wettability of samples was between around 25° and 104°. The SM sample possessed the lowest contact angle. In vitro tests were employed in the simulated body fluid (SBF) solution for 28 days. The samples with different surface textures demonstrated bioactive behaviors. In vitro test results showed that apatite layers formed on the surfaces. The SM sample exhibited good apatite formation ability when the Ca/P ratios were considered. The apatite formation for the SM sample might derive from high roughness, low contact angle value, the existence of Ti-OH groups, and anatase and rutile phases. The SM can be implemented to boost bioactivity on EBM Ti-6Al-4V alloys.

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 °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 energy-dispersive X-ray analysis (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 (Rct) layer. It is expected that this work could provide a promosing way for fabricating Zn-based photocatalyts in environmental redemediation.

Structural colorization with photonic crystal structures draws high attention with fadeless bright color, combined with low toxic and eco-friendly features. It has been suggested for the first that the Titanium (Ti) surface coloration, which was not explained properly until now, is due to the photonic crystal structure. A dyeing process to be applied on the Ti/TiO2 will dampen their photocatalytic properties. However, the thin film grown on the Ti surface by the suggested anodizing process allows the formation of harmless structural colors and keeps photocatalytic performance. Ti substrates were anodized in HF and H3PO4 based solutions at voltage values between 10 V and 80 V. Structural, morphological, optical, and photocatalytic properties of the TiO2 thin films were characterized in order to determine anodization solution type and voltage. Similar to some butterfly wings, it is mentioned that the repeated lamellar and porous structures observed on the surfaces cause photonic crystal interactions with dielectric variations. It can be said that the anodization voltage value but not the anodization solution type can control the obtained structural violet, blue, yellow, orange, and red colors. Samples anodized at lower voltages exhibited better photocatalytic performance due to higher photon harvesting. Thus, we have proved in our study that both the photocatalytic property is not extinguished and that structural colors can be obtained.

In this study, Zinc oxide (ZnO) nanowires (NWs) were successfully produced on Zn plates through electrochemical anodization in potassium bicarbonate aqueous electrolytes with different production parameters in two groups as applied voltage and anodization time. Subsequently, the ZnO NWs were annealed at 300 ℃ for 1 h in air atmosphere to increase crystallinity and remove organic residues. Structural and morphological properties were determined through X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The effect of anodization parameters on the structure of ZnO NWs and thus their photocatalytic activities were evaluated in detail by UV spectrophotometer. The results pointed out that, the most effective nanostructure on the photocatalytic degradation of methylene blue was obtained at the sample anodized under 30 V for 30 min at room temperature with 90.6% degradation efficiency among the samples. This result shows that the NW structured ZnO materials are promising to be used as effective photocatalysts in the removal of organic pollutants by solar energy and their conversion to green compounds.

Titanium thin films were deposited on glass and indium tin oxide (ITO) coated glass substrates by radio-frequency (RF) magnetron sputtering under varying sputtering parameters as: power, pressure, substrate temperature and target-substrate distance. The crystalline structure, crystallite size and texture coefficients of the films were evaluated in detail. As the evaluation points out, 100 W, 1.33 Pa ambient temperature and 70 mm were determined as the optimum sputtering parameters for intended crystalline structures. Subsequently, electrochemical anodization experiments were performed via varied electrolytes and under various anodization parameters (voltage, time and electrolyte type) in a two-electrode electrochemical cell using the films obtained through the optimized sputtering parameters. The anodized samples were annealed at 450 °C for 1 h in air in order to obtain anatase transformation and the desired crystalline structure. The surface morphologies and the crystalline structures of the anodized films were evaluated through x-ray diffractometer (XRD) and scanning electron microscope (SEM), respectively. Finally, the anodization parameters for the formation of TiO2 nanotube arrays were determined as: 35 V and 35 min. in an electrolyte composed of 0.3 wt.-% NH4F – 2 wt.-% water – ethylene glycol.

In this study, silver (Ag)-doped titanium dioxide/reduced graphene oxide (Ag@TiO2/rGO, TGA) hybrid photocatalysts were synthesized for enhanced photocatalytic properties. TGA hybrid photocatalysts were synthesized through a facile sol-gel method. Synthesis of graphene oxide (GO) nanoparticles were obtained by Hummer's method followed by chemical reduction to obtain rGO nanoparticles. Ag doping was carried out at the sol stage of the sol-gel synthesis. Increasing amounts of Ag nanoparticles from 0.5 wt.% to 4 wt.% were added to increase the degradation effect of methylene blue (MB) under UV light irradiation. X-ray diffractometry (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), UV-vis spectrophotometry, photoluminescence spectroscopy (PL), and diffuse reflectance spectroscopy (DRS) were used to investigate the crystal structure, topography, morphology, chemical and optical properties of the samples, respectively. Samples were calcined in order to obtain the anatase phase at 500 degrees C with a heating rate of 10 degrees C/min for 2 h in air atmosphere. The effect of Ag content on the photocatalytic properties of TiO2 based nanocomposite material was observed by keeping the weight ratio of rGO constant at 4 wt.%. Ag addition into the TiO2/rGO matrix exposed an excellent photocatalytic activity under UV light irradiation than that of undoped TiO2/rGO photocatalyst. The absorbance value of MB was degraded from 0.683 to 0.011 at 664 nm by TGA1 sample for 240 min. This demonstrated that the TGA1 hybrid photocatalyst containing 1 wt.% of Ag exhibited the highest degradation efficiency of 98.4%. This paper indicates the potential photocatalytic application of Ag-doped TiO2/rGO photocatalysts on the removal of dissolved organic pollutants in water.

İleri oksidasyon teknolojilerinden biri olan fotokatalitik bozunma, organik kirleticilerin temizlenmesinde ve su arıtımında ümit verici yöntemlerden biri olmaya başlamıştır. Fotokatalistler arasında en dikkat çekeni ise, yüksek fotoaktiviteye sahip, kararlı ve düşük maliyetli olan titanyum dioksit (TiO2) yarı iletken malzemesidir. Bu çalışmada TiO2 kaplamalar, fosforik asit (H3PO4) içerikli elektrolit içerisinde saf titanyumun anodik spark oksitleme metodu ile anotlanması sonucu üretilmiştir. Farklı elektrolit konsantrasyonlarının (0.25-2 M H3PO4) altık yüzeyinde oluşan TiO2’nin mikroyapısına, yüzey morfolojisine ve fotokatalitik performansına olan etkileri incelenmiştir. TiO2 kaplamaların kristalin fazları X ışını kırınım cihazı (XRD) ile belirlenmiştir. Yüzeylerin mikroyapısı, taramalı elektron mikroskobu (SEM) ile analiz edilmiştir. Örneklerin fotokatalitik aktivite testleri, farklı zaman aralıklarında UV ışık altında metilen mavisi çözeltisinin bozundurma çalışmaları ile saptanmıştır. En yüksek fotokatalitik aktivite 1 M elektrolit konsantrasyonunda üretilen TiO2 kaplamasında elde edilmiştir. Deneysel çalışma sonuçları, hem morfolojideki hem de kristal yapıdaki değişikliklerin TiO2 kaplamaların fotoaktivitesi üzerinde güçlü bir etkiye sahip olduğunu göstermiştir.&nbsp, Photocatalytic degradation, one of the advanced oxidation technologies, has begun to be one of the promising methods for cleaning organic contaminants and for water treatment. The most notable among photocatalysts is titanium dioxide (TiO2) semiconducting material with high photoactivity, stable and low cost. In this study, TiO2 coatings were produced by anodic spark oxidation method on pure titanium in H3PO4 containing electrolyte. The effects of different electrolyte concentrations (0.25-2 M H3PO4) on the microstructure, surface morphology and photocatalytic performance of TiO2 coatings have been investigated. The crystalline phases of the TiO2 coatings obtained were determined by XRD. The microstructure of the surfaces was analyzed by SEM. The photocatalytic activity tests of the samples were evaluated by the degradation of aqueous methylene blue solutions under UV light at different time intervals. The highest photocatalytic activity was obtained in the TiO2 coating produced in a 1 M electrolyte concentration. The results indicated that changes in both the morphology and crystalline structure have a strong influence on the photoactivity of the TiO2 coatings.&nbsp

In the present study, cuprous oxide (Cu2O)and cupric oxide (CuO) structures were prepared by thermal oxidation of electroplated copper (Cu) coatings on titanium substrates. The influence of different annealing temperatures from 200 to 600 degrees C on the morphology, crystal structure and the photocatalytic activity of the Cu2O and CuO structures were studied in detail. The photocatalysts were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Photocatalytic activities of the samples were examined by the degradation of methylene blue (MB) under UV light irradiation. The spectroscopic analysis was investigated by UV vis spectrophotometer. The results showed that the microstructure and surface morphology of the samples changed considerably at different annealing temperatures. The sample annealed at 500 degrees C exhibited the highest photocatalytic activity. The results indicated that need-like surface morphology and phase structure play an important role in enhancement the photocatalytic performance of Cu2O/CuO structures. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

In this study, we present results of comparative studies on the microstructure and mechanical properties of nanostructured and microstructured titanium dioxide (TiO2) films formed on titanium substrates by electrochemical anodization at different electrolytes. Nanostructured TiO2 film was prepared in 1% HF solution for 30 min. Microstructured TiO2 films were anodized in two different electrolytes (1 M H2SO4 and 1.4 M H3PO4) for 10 min. The phase structures, surface morphologies and surface topographies of the samples were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscopy (AFM), respectively. The surface hardness and elastic modulus of the TiO2 films were studied using nanoindentation technique. The results showed that the electrolyte type and applied voltage have a strong influence on the morphology and crystalline structure of the TiO2 films. It was found that hardness and elastic modulus of the nanostructured TiO2 film were much lower than the microstructured TiO2 films. (C) 2016 Elsevier B.V. All rights reserved.

In this study, undoped and Zn-doped SnO2 nanoparticles in different concentrations were synthesized by flame spray pyrolysis (FSP) technique. The produced particles were post-annealed after FSP process at 600 °C in order to obtain a crystalline structure. The structural analysis of the produced powders was performed by X-Ray Diffraction (XRD) methods. The surface morphology of the nanoparticles was identified using scanning electron microscopy (SEM). In addition, photocatalytic degradation of aqueous methylene blue (MB) solutions were evaluated using undoped and Zn-doped SnO2 nanoparticles under UV light illumination. Photocatalytic degradation of the MB solutions followed the pseudo-first-order-kinetics and the effect of the Zn doping amount on the photocatalytic reaction was investigated. © 2018, Turkish Chemical Society. All rights reserved.

Porous titanium dioxide (TiO2) coatings were prepared on the pure titanium substrate by anodic spark oxidation (ASO) method in electrolytes containing various concentrations of sulfuric acid. The crystal phase, surface morphology, chemical composition, and optical property of the TiO2 films were analyzed by using XRD, SEM, XPS, and UV-vis spectroscopy. The photocatalytic activity is evaluated by the decomposition of methylene blue (MB) aqueous solution under UV light irradiation. It is found that the electrolyte concentration plays an important role in the properties and characteristics of the TiO2 coatings. The results show that TiO2 films consist of primarily the rutile phase with altering fraction depending on the electrolyte concentration without any heat treatment. The results demonstrated that there were formed too many sub-micron and nanopores of TiO2 neighboring to the micropores. TiO2 layer anodized in 0.75 M H2SO4 exhibited much higher photocatalytic activity than the other films. The results imply that anatase-rutile mixed TiO2 coatings can be successfully used for the photocatalytic degradation of organic pollutants.

In this study, nanostructured anatase titanium dioxide (TiO2) films were fabricated by electrochemical anodization of titanium first, and then annealed at 500 degrees C for 2 h. Effect of electrolyte concentration, anodization time and electrolyte temperature on the surface morphology of the resulting TiO2 thin films were investigated. The phase structures, surface morphology and chemical composition were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity tests of the samples were evaluated by the degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods of time. The results showed that the structure of nanostructured TiO2 films depended strongly on the anodization parameters. It was found that there were micro-scale pores (

The aim of this study was to evaluate the effect of electrolyte concentration on the surface morphology, surface topography, wettability and surface roughness of nanoporous titanium dioxide (TiO 2 ) layers. Titanium (Ti) samples were treated by sandblasting and acid-etching processes. TiO 2 layers were formed on sandblasted/acid-etched titanium in electrolytes containing different HF concentration (% 0.25-2). The samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface roughness and the wettability of the samples were measured using proilometry and a contact angle measurement system. The samples, which were anodized after sandblasting/acid-etching treatment had amorphous structure and peaks from the substrate were observed. The results showed that with increasing HF concentration, the surface morphology of the samples were significantly changed. All the treated samples exhibited hydrophilic properties.

In this study, micro-nanoporous TiO2 films were prepared by electrochemical anodization of titanium (Gr-2) in an aqueous solution containing 0.5 wt. % HF solution at a constant potential of 30 V and then annealed in ambient air at 500, 600, 700 and 800 °C for 2 h to obtain crystalline structures. The crystalline phase and surface morphology of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic performances of the samples were evaluated by the photocatalytic degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods. XRD results indicated that at annealing temperatures higher than 600°C, anatase started to transform into rutile. Increasing annealing temperatures resulted in reduced micro-nanopores diameter and increased wall thickness. At 800°C, the structure completely disappeared. The results demonstrated that changes in both the crystalline structure and surface morphology have a strong influence on the photoactivity of the nanostructured TiO2 films. © 2018, Turkish Chemical Society. All rights reserved.

Zinc oxide (ZnO) is widely used in different areas thanks to its unique photocatalytic, optic and electrical properties. Sn doped ZnO nanoparticles were synthesized through flame spray pyrolysis (FSP) technique. The Sn dopant concentrations were 1, 3, 5, 7 and 9 at. % in produced ZnO nanoparticles. The structural analysis of the produced powders was performed by X-Ray Diffraction (XRD) methods. The surface morphology and particle size distribution of the nanoparticles were identified using scanning electron microscopy (SEM), and dynamic light scattering (DLS) techniques. In addition to this, produced photocatalysts were evaluated for degradation of aqueous methylene blue (MB) solutions under UV light irradiation. Sn-doped nanoparticles have superior photocatalytic activity compared to un-doped ZnO. © 2018, Turkish Chemical Society. All rights reserved.

In this work, zinc oxide (ZnO) nanostructures were successfully synthesized by thermal oxidation of zinc (Zn) coated steel substrates. Zn coatings were electrodeposited on the mild carbon steel sheet in the sulfate bath by DC current. The zinc coated samples were oxidized in air at distinct annealing temperatures between 400 degrees C and 800 degrees C. The phase structure and surface morphology of the ZnO films were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activity of these ZnO layers was examined by means of decomposition of methylene blue (MB) aqueous solutions under DV lamp irradiation for various duration. The findings illustrated that annealing temperatures had a big effect on the morphology and structure of the ZnO layers. The annealed layers showed significantly enhanced photoactivity activity than the pure Zn layer under UV-irradiation. The sample with ZnO nanostructures oxidized at 800 degrees C exhibited a better photocatalytic degradation of MB than the other samples. This paper can provide an important contribution to the development of efficient photocatalysts for the solution of the environmental pollution problems.

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.

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.

In this paper, we present results of comparative studies on the photocatalytic activity of microporous and nanoporous titanium dioxide (TiO2) layers formed on titanium substrates by electrochemical anodization at different voltages. Two sample groups each including four samples was prepared for microporous and nanoporous TiO2 layer formation. Microporous TiO2 layers were prepared in 1 M H2SO4 solution in 10 min. Nanoporous TiO2 layers were formed in %1 HF solution in 30 min and then annealed at 480 degrees C in ambient air. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The photocatalytic activity of the samples was determined by assessing the decomposition rate of methylene blue (MB) solutions under UV light for different periods of time. By using the data obtained from the UV-Visible spectrophotometer, photocatalytic decomposition kinetics was also determined. The results indicated that nanoporous TiO2 layers formed by applying 20 V showed optimal photocatalytic performance, whereas the sample anodized at 250 V exhibited the highest photocatalytic activity within its own sample group, nearly matching the photocatalytic activity of the highest performing sample. (C) 2015 Elsevier B.V. All rights reserved.

Nanoporous titanium oxide (TiO2) layers were fabricated on commercially pure titanium (Cp-Ti) substrates by the anodic oxidation method under a potentiostatic regime. Anodic oxidation was performed in an aqueous solution containing 1 wt% hydrofluoric acid at room temperature for 30 min. Subsequently one of the anodized samples was annealed at 480 degrees C for 2 h in air in order to obtain anatase transformation and increased crystallinity. The average pore diameter of both anodized and anodized+annealed samples were found to be nearly 52 nm and 66 nm, whilst the average inter-pore distances were approximately 65 rim and 76 nm, respectively. Characterization of nanoporous TiO2 layers was carried out through X-ray diffractometer (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV visible spectroscopy. Effects of heat treatment on properties such as crystallinity, morphology and photocatalytic activity were investigated in details. Finally photocatalytic degradation ratios and changes in degradation kinetics under the presence of both anodized and anodized+annealed catalysts were calculated. Depending on the obtained results, the annealed film with anatase structure demonstrated highly efficient photacatalytic performance. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Nanoporous titanium dioxide (TiO2) layers were successfully formed by an electrochemical anodisation method on microroughened titanium (Ti) surfaces in fluoride containing aqueous electrolyte. Microroughened Ti surfaces were produced by sandblasting with Al2O3 particles of 50 μm in diameter and acid-etching in a blend of HCl/H2SO4 solution. The surface morphology, topography and chemical composition of the specimens were analysed by scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The surface roughness and the wettability of treated Ti surfaces were measured using profilometry and a contact angle measurement system, respectively. With anodising of sandblasted-/acid etched surfaces, micrometre- and nanometre-scale textures on titanium specimens were created. Results showed that these developed nanoporous-microroughened surfaces exhibited lower contact angle values than the other treated Ti surfaces. The sandblasted/acid-etched/anodised Ti specimen had a surface morphology with distinctively formed hills and valleys and higher surface roughness than the other anodised specimens. This study indicated that nanoporous TiO2 structures fabricated on microroughened Ti can be an effective way to modify the titanium surfaces for the future development of implant applications., BAP (Department of Scientific Research Projects) 2011.KB.FEN.029; EMUM (Center for Fabrication and Application of Electronic Materials) in Dokuz Eylul University