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1.
T. Kubart  J. Jensen  L. Liljeholm  S. Berg 《Vacuum》2009,83(10):1295-1298
Titanium dioxide thin films have many interesting properties and are used in various applications. High refractive index of titania makes it attractive for the glass coating industry, where it is used in low-emissivity and antireflective coatings. Magnetron sputtering is the most common deposition technique for large area coatings and a high deposition rate is therefore of obvious interest. It has been shown previously that high rate can be achieved using substoichiometric targets. This work deals with reactive magnetron sputtering of titanium oxide films from TiOx targets with different oxygen contents.The deposition rate and hysteresis behaviour are disclosed. Films were prepared at various oxygen flows and all films were deposited onto glass and silicon substrates with no external heating. The elemental compositions and structures of deposited films were evaluated by means of X-ray photoelectron spectroscopy, elastic recoil detection analysis and X-ray diffraction. All deposited films were X-ray amorphous. No significant effect of the target composition on the optical properties of coatings was observed. However, the residual atmosphere is shown to contribute to the oxidation of growing films.  相似文献   

2.
Polyaniline films prepared on titanium were employed as substrate for the electrodeposition of gold. The modified electrode was used as anode for the electro-oxidation of ascorbic acid. The electrochemical behavior and electro-catalytic activity of Au/PAni/Ti electrode were characterized by cyclic voltammetry. The morphology of the polyaniline film and gold coating on PAni/Ti electrode were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) techniques, respectively. Results indicated that gold nanoparticles were homogeneously dispersed on the surface of polyaniline film. The electro-oxidation of ascorbic acid is found to proceed more facile on Au/PAni/Ti electrode than on bare gold electrode. The irreversible oxidation current of ascorbic acid exhibits a linear dependence on the ascorbic acid concentration in the range of 1–5 mM.  相似文献   

3.
This paper describes the formation of self-organized nanopores in thin films of titanium prepared using a Filtered Cathodic Vacuum Arc (FCVA) deposition system. The post-deposition anodization was performed using 0.5% (wt) NH4F in ethylene glycol and an aqueous based solution containing 0.5% (wt) NH4F and 1 M (NH4)2SO4 electrolytes. Homogenously distributed nanopores with dimensions in the range of 10 to 20 nm were obtained. Nanoporous TiO2 thin films were obtained after annealing the anodized samples at 600 °C for 4 h. Scanning electron microscopy (SEM) and Raman spectroscopy were used to characterize these nanoporous films. Raman measurements revealed that the rutile TiO2 polymorph dominates these structures along with imperfect titanium oxidation resulting in the formation of defect structures, particularly when aqueous electrolyte was used for the anodization.  相似文献   

4.
The multi-layer TiO2 nanotube array thin films have been formed by anodic oxidation method via adjusting the outer voltage during oxidation process in glycerol electrolyte containing 0.3% NH4HF2. The diameter of the nanotube array increases with the outer voltage, and the length of nanotube in every layer increases with the anodic oxidation time. These multi-layers bring new possibilities to tailor the properties of the TiO2 nanotube array thin films formed via anodic oxidation method. Further, such multi-layer structure provide a new approach to evaluate the growth rate of TiO2 nanotube, which will help us to understand more deeply the formation mechanism of the TiO2 nanotubes. The growth rate of TiO2 nanotube array is respectively 1.2 and 3.6 μm/h under the anodic voltage of 30 V and 60 V. These multi-layer TiO2 nanotube array thin films may exhibit lots of potential applications in photoelectrochemical fields.  相似文献   

5.
Yaw-Nan Shieh 《Thin solid films》2010,518(24):7464-6939
Nano-crystalline TiO2 thin films were synthesized by using sol-gel and spin-coating techniques on glass substrates for photo-catalytic applications. Prior to deposition, a TiO2 colloidal suspension was synthesized by microwave-induced thermal hydrolysis of the titanium tetrachloride aqueous solution. In this study, the deposited TiO2 coating with a grain size of 13 ± 2 nm was uniform without aggregation. Co ion implantation into the as-calcined TiO2 thin films was conducted with fluences of 1 × 1015-1 × 1016 doses/cm2 at 40 keV. In addition to the emission of TiO2, the photoluminescence study showed the presence of another Co-related optical center at 405 nm in the Co-implanted TiO2 thin films. Due to the strong capability of forming impurity compounds between the energetic cobalt ions and TiO2, the photoluminescence emission and UV-Vis absorption efficiencies were improved.  相似文献   

6.
Well-aligned TiO2/Ti nanotube arrays were synthesized by anodic oxidation of titanium foil in 0.5 wt.% HF in various anodization voltages. The images of filed emission scanning electron microscopy indicate that the nanotubes structure parameters, such as diameter, wall thickness and density, can be controlled by adjusting the anodization voltage. The peaks at 25.3° and 48.0° of X-ray diffraction pattern illuminate that the TiO2 nanotube arrays annealed at 500 °C are mainly in anatase phase. The filed emission (FE) properties of the samples were investigated. A turn-on electric field 7.8 V/µm, a field enhancement factors approximately 870 and a highest FE current density 3.4 mA/cm2 were obtained. The emission current (2.3 mA/cm2 at 18.8 V/µm) was quite stable within 480 min. The results show that the FE properties of TiO2/Ti have much relation to the structure parameters.  相似文献   

7.
Mesoporous TiO2 thin films were prepared by hydrothermal-oxidation of titanium metal thin films, which were obtained by DC magnetron sputtering technique. Gold nanoparticles, which were prepared by reduction of HAuCl4, were embedded into the holes of the mesoporous TiO2 films by capillary method followed by annealing in air up to 400 °C. The size of pore of TiO2 films is about 100 nm and that of Au nanoparticles is about 10 nm in average. The morphology of the films was analyzed by field emission scanning electron microscope (FE-SEM) and scanning probe microscopes (SPMs). Subsequently, the photocatalytic performances of the obtained nanosystems in the decomposition of methylene blue solution are discussed. The obtained results show that the dispersion of Au nanoparticles on the mesoporous TiO2 matrix will help enhancing the photocatalytic activity with respect to pure TiO2 under visible light irradiation.  相似文献   

8.
Determining the concentration of hydrogen peroxide (H2O2) is of great importance in food, pharmaceutical, environmental and clinical analyses. Horseradish peroxidase (HRP), an enzyme specifically catalyzing the oxidative reaction of H2O2 to develop color reaction, has been widely used for measuring H2O2 concentration. However, owing to the instability and high cost of this enzyme, discovering efficient mimics of peroxidase has been important to conquer these disadvantages of protein catalyst. Recently we have found that Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) possess intrinsic peroxidase-like activity, which can catalyze oxidation of various peroxidase substrates in the presence of H2O2. Based on this finding, we developed a spectrometric method using Fe3O4 MNPs as a catalyst to determine H2O2 in rainwater. Our data show that the Fe3O4 MNPs are efficient catalysts to determine H2O2 in rainwater. Compared to HRP, the Fe3O4 MNPs are reusable and economical and these characteristics make the particles a board range of applications in determining H2O2 in the rainwater.  相似文献   

9.
Rutile TiO2 nanorod films have been successfully prepared on titanium substrate via a hydrothermal method using Tetra-n-butyl titanate as Ti source in the presence of concentrated hydrochloric acid. The effect of Ti substrate annealing treatment and adding of additional alkali metal chlorides in hydrothermal solution on the growth of TiO2 nanorod films has been studied using scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and water contact angle measurement. The growth mechanism of the TiO2 nanorods on Ti substrate has also been discussed. It has shown that the initial rutile film transformed from anatase promotes the nucleation and epitaxial growth of rutile TiO2 nanorods. The superior wettabilities of the TiO2 nanorods resulted from treatments of vacuum and ultraviolet show great potential for applications in orthopaedic, dental implants, and possible photocatalysis.  相似文献   

10.
Titanium hydride is well known for its stability in air because of formation of thin TiO2 oxide layer on top of TiH2 powder particles. Formation of the oxide layer is directly related to high affinity of Ti to oxygen and it can be formed in few seconds also on top of TiH2 particles in low vacuum. On the other hand, thickness of TiO2 layer on the formed TiH2 powder is in the range of 130 nm. Existence of oxide layer on top of powder particles was confirmed with AES, XPS and EDXS cross section line scans. Formation of thin oxide was confirmed also with calculations based on chemical and TG analyses.  相似文献   

11.
Flagella isolated from Salmonella typhimurium were used as a template for the formation of TiO2 nanotubes, which was accomplished through recent advances in low temperature ceramic film processing. TiO2 is precipitated onto or attracted to the flagellar surface in aqueous solution. The mechanism of mineral film formation is similar to that of biominerals in nacre, sea urchin spine, and sponge spicule. This process is advantageous over other mineralization processes, as no genetic modification of the flagella is necessary and the mineralization is done at low temperature in aqueous solution.  相似文献   

12.
This work presents the influence of annealing on the structure and stoichiometry of europium (Eu)-doped titanium dioxide (TiO2). Thin films were fabricated by magnetron sputtering from a metallic Ti-Eu target in oxygen atmosphere and deposited on silicon and SiO2 substrates. After deposition the selected samples were additionally annealed in air up to 1070 K.Film properties were examined by means of X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) and the results were analyzed together with the undoped TiO2 thin films prepared under similar technological conditions.XRD results showed that depending on the Eu content, as-deposited thin films consisted of the TiO2-anatase or TiO2-rutile.An additional annealing will result in the growth of anatase crystals up to 35 nm, but anatase to rutile phase transformation has not been recorded. AFM images display high quality and a dense nanocrystalline structure. From the XPS Ti2p spectra the 4+oxidation state of Ti was confirmed. The O1s XPS spectra displayed the presence of an O2− photoelectron peak accompanied by an additional broader peak that originates from hydroxyl species chemisorbed at the sample surface. It has been found that Eu dopant increases the OH content on the surface of prepared TiO2:Eu thin films. The calculated O/Ti ratio was in the range of 1.85-2.04 depending on the sample.  相似文献   

13.
Indigenously available natural dyes have been used as natural sensitisers for dye-sensitised solar cells (DSSCs) in this study. The chlorophyll extract from Azadirachta indica (Neem) leaves and anthocyanin extract from poinsettia bracts were obtained using ethanol. Nanoparticles of TiO2 having an average size of 80 nm were deposited on fluorine-doped tin oxide (FTO) coated glass using the electrophoretic deposition method. Counter electrode was prepared by spraying conductive graphite over FTO glass substrates. A sandwich-type cell was assembled, and the fill factor and the power conversion efficiency were measured under a light source simulating AM 1.5 with an intensity of 100 mW/cm2. DSSCs containing chlorophyll and anthocyanin exhibited open circuit voltages of 404 and 406 mV with fill factors of 40.1% and 45.8%, respectively. The mixture of the two natural dyes as sensitiser for DSSCs gave the best photovoltaic conversion efficiency of approximately 1%.  相似文献   

14.
The multi-staged formation process of titanium oxide nanotubes was investigated in detail under a hydrothermal treatment. During the synthesis procedure, an intermediate stage (tree-like structures) was observed before the formation of the titanium oxide layered structures. The layered structure of titanium oxide generally was considered to exfoliate directly from raw TiO2 materials through the alkaline hydrothermal treatment. The rolling process of the layered structures of titanium oxide was confirmed by TEM observation after the alkaline hydrothermal treatment for the raw TiO2 materials, followed by washing with 4 M HNO3 aqueous solution. The thermal stability of the tube products was investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The result showed that both the morphology and crystal phase of titanium oxide nanotubes could be retained even after calcination at 650 °C.  相似文献   

15.
Arrays of TiO2 nanotubes were fabricated by the anodization of Ti foils and then used in assembling dye-sensitized solar cells (DSSCs). The role of the morphologies of the TiO2 nanotubes in the photovoltaic performances of the DSSCs was studied in terms of the surface topography and the tube length. The necessity of removing the nanoporous films from the surface of the nanotube arrays for good DSSC performance has been demonstrated. Also, it has been shown that appropriately increasing the tube length was an effective measure for enhancing both the short-circuit current density and the conversion efficiency of the DSSCs.  相似文献   

16.
This paper demonstrates a new method to grow nano-structured TiO2 over a plasma electrolytically oxidised titanium surface. Microstructural characterisation by employing a variety of transmission electron microscopy techniques was carried out to explore the nano-scale structural changes due to the alkaline and thermal treatments. Photovoltaic performance was measured and this revealed the effect of microstructural changes. Such coatings can be considered potential candidates for the electrode material in a dye-sensitised solar cell (DSSC). The experimental results show that a titania layer with a 3D network ‘nano-flaky’ surface can be successfully prepared. The obtained nano-flakes are around 100 to 200 nm across and have a thickness of less than 10 nm. These completely cover the outermost surface as well as the inner pores and voids. The formed nano-flaky structure is amorphous and provides a larger surface area for dye absorption to increase the efficiency of assembled DSSC. Thermal annealing treatment causes the transformation of the amorphous nano-flakes into anatase nano-crystallites and further enhances the photovoltaic efficiency of the assembled DSSC.  相似文献   

17.
In this study, electrospun nylon-6 spider-net like nanofiber mats containing TiO2 nanoparticles (TiO2 NPs) were successfully prepared. The nanofiber mats containing TiO2 NPs were characterized by SEM, FE-SEM, TEM, XRD, TGA and EDX analyses. The results revealed that fibers in two distinct sizes (nano and subnano scale) were obtained with the addition of a small amount of TiO2 NPs. In low TiO2 content nanocomposite mats, these nanofiber weaves were found uniformly loaded with TiO2 NPs on their wall. The presence of a small amount of TiO2 NPs in nylon-6 solution was found to improve the hydrophilicity (antifouling effect), mechanical strength, antimicrobial and UV protecting ability of electrospun mats. The resultant nylon-6/TiO2 antimicrobial spider-net like composite mat with antifouling effect may be a potential candidate for future water filter applications, and its improved mechanical strength and UV blocking ability will also make it a potential candidate for protective clothing.  相似文献   

18.
The flux of energetic negative ions was measured during the preparation of TiO2 in Ar/O2 as a function of oxygen partial pressure. The Ti surface was so active that the small amount of O2 contained in Ar was sufficient to oxidize the target surface. Ti target is also oxidized as similarly to the other metals such as Zr and Zn. Oxide islands form, which coalesce and cover the target surface with an oxide layer. The thickness of the Ti oxide layer on the target surface increased with increasing target current and Ar/O2 gas pressure, which increased the oxygen flux incident on the target. This is due to the high reactivity of the Ti surface with oxygen. The data revealed that the flux of energetic negative ions in reactive sputtering of Ti in Ar/O2 is fairly small compared with the sputtering of Zr and Zn. This indicates that the generation rate of negative ions on the Ti target during the reactive sputtering is very small.  相似文献   

19.
This study examined the characterization of nanoporous structured titanium dioxide and its application to dye-sensitized solar cells (DSSCs). TEM revealed nanopore sizes of 10.0 nm with a regular hexagonal form. When nanoporous structured TiO2 was applied to DSSC, the energy conversion efficiency was enhanced considerably compared with that using nanometer sized TiO2 prepared using a hydrothermal method. The energy conversion efficiency of the DSSC prepared from nanoporous structured TiO2 was approximately 8.71% with the N719 dye under 100 mW cm−2 simulated light. FT-IR spectroscopy showed that the dye molecules were attached perfectly to the surface and more dye molecules were absorbed on the nanoporous structured TiO2 than on the nano-sized TiO2 particles prepared using a conventional hydrothermal method. Electrostatic force microscopy (EFM) showed that the electrons were transferred rapidly to the surface of the nanoporous structured TiO2 film.  相似文献   

20.
Copper oxide nanotubes decorated by TiO2 nanoparticles (CNTNs) were fabricated by simple three-step method. First, deposition of copper onto cellulose fibres, then thermal oxidation of copper and cellulose fibres and last simply mixing copper oxide nanotubes and TiO2 nanoparticles (NPs). Scanning electron microscopy, transmission electron microscopy and X-ray diffraction showed that the synthesised nanotubes were monoclinic-structured polycrystalline CuO with diameter and wall thickness of approximately 50~100 nm and 20~25 nm, respectively. Moreover, the diameter of the TiO2 NPs is about 20~30 nm. Optical properties of the solutions containing copper oxide nanotubes decorated by TiO2 NPs were studied. Discrete dipole approximation was used for the calculation of absorption, scattering and extinction cross sections of the deposited CNTNs on a glass substrate. Our simulation results show that there are good agreements between the experimental date and the simulation results. Moreover, the photocatalytic tests were done by methyl orange under visible light (λ = 633 nm) irradiation for prepared samples.  相似文献   

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