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1.
The partial current densities for the transfer of titanium(IV) and oxygen ions, and of electrons at the interface between the electrolyte and the titanium(IV) oxide layer on titanium were measured as functions of total current density and pH value. It is shown theoretically, how conclusions regarding the mechanisms of the transfer reactions of both ions can be drawn from various relations between the ionic partial current densities and their dependence on solution composition, even if the electric potential difference at the oxide interface cannot be measured. Mechanisms for the transfer reactions of titanium(IV) and oxygen ions are derived from the experiments. 相似文献
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Petr Kluson Stepan Kment Magdalena Morozova Pavel Dytrych Stanislav Hejda Morwenna Slater Zdenek Hubicka Josef Krysa 《Chemical Papers》2012,66(5):446-460
Chemistry and physics of thin semiconducting layers of various types are subjects of intense research. Especially when nanotechnology methods such as self-assembly are involved, amazing structural and/or functional properties may appear. Also modern physical methods using variously organized plasma arrangements are able to produce uniform structures with distinctive functionality. In this review, based virtually on our own work, discussions on the preparation, structure, morphology, and function of titanium(IV) oxide nanoscopic thin films are presented. It was shown that structurally and functionally similar titanium(IV) oxide films can be prepared via completely different preparation techniques. Function tests were arranged as “primary”, covering the assessment of the light induced charge separation efficiency, and “secondary”, based on photocatalytic surface oxidations. 相似文献
4.
Chandra D Ohji T Kato K Kimura T 《Physical chemistry chemical physics : PCCP》2011,13(27):12529-12535
Titania films having relatively uniform spherical pores were successfully fabricated using polystyrene-block-poly(ethylene oxide) (PS(n)-b-PEO(m)) diblock copolymers. Depending on the molecular weight of PS(n)-b-PEO(m), the spherical pores were varied from large mesopores (n = 40,000, m = 53,000; ~40 nm) to macropores (n = 58,600, m = 71,000; ~60 nm, n = 100,000, m = 150,000; ~100 nm) in diameter. It was confirmed that the porous structures were thermally stable with crystallization of the titania frameworks. Interconnectivity between the spherical pores was reliant on the micellar arrangement of hydrophobic PS cores, while the amount of isolated pores was increased in the films prepared using low molecular weight PS(n)-b-PEO(m). The presence of such isolated pores was confirmed on the basis of adsorption experiments by using a globular hemoprotein cytochrome c (ca. 3.1 nm). Highly interconnected spherical pores, which were preferentially fabricated using high molecular weight PS(n)-b-PEO(m), were quite helpful for smooth diffusion-adsorption of bulky proteins inside the porous films. 相似文献
5.
Kern P Müller Y Patscheider J Michler J 《The journal of physical chemistry. B》2006,110(47):23660-23668
Electrolytically deposited amorphous TiO2 films on steel are remarkably sensitive to electron beam (e-beam) irradiation at moderate energies at 20 keV, resulting in controlled local oxide reduction and crystallization, opening the possibility for local topographical, chemical, and structural modifications within a biocompatible, amorphous, and semiconducting matrix. The sensitivity is shown to vary significantly with the annealing temperature of as-deposited films. Well-defined irradiation conditions in terms of probe current IP (5 microA) and beam size were achieved with an electron probe microanalyzer. As shown by atomic force and optical microscopy, micro-Raman spectroscopy, wavelength-dispersive X-ray (WDX), and Auger analyses, e-beam exposure below 1 Acm-2 immediately leads to electron-stimulated oxygen desorption, resulting in a well-defined volume loss primarily limited to the irradiated zone under the electron probe and in a blue color shift in this zone because of the presence of Ti2O3. Irradiation at 5 Acm(-2) (IP = 5 microA) results in local crystallization into anatase phase within 1 s of exposure and in reduction to TiO after an extended exposure of 60 s. Further reduction to the metallic state could be observed after 60 s of exposure at approximately 160 Acm(-2). The local reduction could be qualitatively sensed with WDX analysis and Auger line scans. An estimation of the film temperature in the beam center indicates that crystallization occurs at less than 150 degrees C, well below the atmospheric crystallization temperature of the present films. The high e-beam sensitivity in combination with the well-defined volume loss from oxygen desorption allows for precise electron lithographic topographical patterning of the present oxides. Irradiation effects leading to the observed reduction and crystallization phenomena under moderate electron energies are discussed. 相似文献
6.
A. H. J. van den Berg W. Lisowski M. Smithers 《Analytical and bioanalytical chemistry》1999,365(1-3):231-235
Thin titanium and titanium oxide films, both covered by ultra-thin gold layers, have been compared with titanium films after
analysis, using a combination of SEM and AES. The Ti films were prepared under UHV conditions by evaporation on a glass substrate.
The Ti oxide layers were prepared in situ by precisely controlled oxygen sorption at 298 K on Ti film. Both Ti and Ti oxide
films were then covered in situ by a very thin Au layer. Analysis was performed in a separate system after long-term exposure
of the films to air. SEM analysis revealed a much smaller size grain on the Au coated Ti films than on Ti films not coated
with a Au layer. The thin gold layers covering the Ti surface prevent an extensive air interaction with Ti film. The analysis
of the features of the Ti Auger spectra during the sputter profile measurements allow to characterise the chemical nature
of Ti-oxide formed in Ti/Au interface region.
Received: 7 September 1998 / Revised: 14 January 1999 / Accepted: 2 February 1999 相似文献
7.
Etienne M Grosso D Boissière C Sanchez C Walcarius A 《Chemical communications (Cambridge, England)》2005,(36):4566-4568
We provide the first electrochemical evidence of permeability changes in continuous mesoporous TiO2 thin film electrodes induced by nanocrystallisation. 相似文献
8.
The electrochemical characteristics of ruthenium oxides, formed on Ru-plated Ti electrodes in 0.5 M H2SO4 by potential cycling with different CV upper potential limits (E
SU), were systematically compared. The repeated potential cycling between 0.2 and 0.75 V activated the formation/reduction of
surface Ru oxides with hysteretic behavior. This application of repeated CVs also modified the ability of Ru deposits for
hydrogen adsorption/desorption. An irreducible Ru oxide accumulated on the electrode at potentials more positive than ca.
0.95 V, whose capacitive characteristics are applicable for electrochemical supercapacitors. This irreducible oxide was composed
of an aggregate consisting of Ru in various oxidation states, bridged oxygen, OH and water in a 3D-like structure with a relatively
ordered and compact nature, from the X-ray photoelectron spectroscopic and voltammetric results. The surface reconstruction
of the Ru deposits induced by the repeated potential cycling with E
SU≥0.75 V was clearly observed from the SEM photographs. From the X-ray diffraction patterns, all the anodically formed Ru oxides
showed an amorphous nature. 相似文献
9.
V. S. Rudnev D. L. Boguta K. N. Kilin P. M. Nedozorov T. P. Yarovaya 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(8):1350-1351
The plasma electrolytic deposition (PED) method is shown to be useful for the formation of zirconium-containing layers in electrolytes containing Zr(IV) polyphosphate complexes. Titanium phosphates, binary titanium-zirconium phosphates, titanium phosphates, and zirconium phosphates crystallize during annealing of PED layers in air. The element and phase compositions depend on the molar ratio n=[polyphosphate]/[Zr4+] in the bulk of the electrolyte. 相似文献
10.
Kong DS 《Langmuir : the ACS journal of surfaces and colloids》2008,24(10):5324-5331
The influence of fluoride (and its concentration) on the electrochemical and semiconducting properties of anodic oxide films formed on titanium surfaces was investigated by performing electrochemical measurements (potentiodynamic/pontiostatic polarization, open circuit potential (OCP), and capacitance measurements) for a titanium/oxide film/solution interface system in fluoride-containing 1.0 M HClO(4) solution. On the basis of the Mott-Schottky analysis, and with taking into account both the surface reactions (or, say, the specifically chemical adsorption) of fluoride ions at the oxide film surface and the migration/intercalation of fluoride ions into the oxide film, the changes in the electrochemical behavior of titanium measured in this work (e.g., the blocked anodic oxygen evolution, the increased anodic steady-state current density, the positively shifted flat band potential, and the positively shifted film breakdown potential) were interpreted by the changes in the surface and the bulk physicochemical properties (e.g., the surface charges, surface state density, doping concentration, and the interfacial potential drops) of the anodic films grown on titanium. The fluoride concentrations tested in this work can be divided into three groups according to their effect on the electrochemical behavior of the oxide films: < or =0.001 M, 0.001-0.01 M, and >0.01 M. By tracing the changes of the OCP of the passivated titanium in fluoride-containing solutions, the deleterious/depassive effect of fluoride ions on the titanium oxide films was examined and evaluated with the parameter of the film breakdown time. It was also shown that the films anodically formed on titanium at higher potentials (>2.5 V) exhibited significantly higher stability against the fluoride attack than that either formed at lower potentials (<2.5 V) or formed natively in the air. 相似文献
11.
Pfaffenroth C Winkel A Dempwolf W Gamble LJ Castner DG Stiesch M Menzel H 《Macromolecular bioscience》2011,11(11):1515-1525
Copolymers of 4-vinyl-N-hexylpyridinium bromide and dimethyl(2-methacryloyloxyethyl) phosphonate self-assemble to form ultrathin layers on titanium surfaces that show antimicrobial activity, and biocompatibility. The copolymer layers are characterized by contact angle measurements, ellipsometry and XPS. Antibacterial activity is assessed by investigation of adherence of S. mutans. Biocompatibility is rated based on human gingival fibroblast adhesion and proliferation. By balancing the opposing effects of the chemical composition on biocompatibility and antimicrobial activity, copolymer coatings are fabricated that are able to inhibit the growth of S. mutans on the surface but still show attachment of gingival fibroblasts, and therefore might prevent biofilm formation on implants. 相似文献
12.
V. D. Parkhomenko A. S. Katashynsky P. N. Tsybulev N. V. Parkhomenko 《Reaction Kinetics and Catalysis Letters》1997,62(2):359-362
The mechanism of NO activation on the surfaces of crystalline titanium monocarbide and titanium mononitride has been studied
within the framework of semiempirical SCF LCAO NDDO method. The adsorption has been shown to be accompanied by electron density
transfer from the crystal surface to the adsorbate molecule. Stronger activation of the NO molecule is observed on the TiC
surface as compared with that on TiN surface. 相似文献
13.
A. N. Ozerin A. N. Zelenetskii T. A. Akopova O. B. Pavlova-Verevkina L. A. Ozerina N. M. Surin A. S. Kechek’yan 《Polymer Science Series A》2006,48(6):638-643
The effect of primary amino groups and molecular mass of chitosan on the stability of suspensions based on nanoscale TiO2 dispersions in acidic solutions of various concentrations at pH 2.5 was studied. In the case of chitosan prepared according to a commercialized process, the stability of TiO2 suspensions was low and depended on the concentration of the polymer solution. Solutions of low-molecular-mass highly deacetylated chitosan prepared by solid-phase synthesis stabilized a dispersion of nanosized TiO2 particles for a very long time. Nanocomposites based on a chitosan-PVA graft copolymer and TiO2 were prepared, in which the initial filler dispersion is retained up to very high filling ratios. A potential use of these nanocomposites in photocatalytic processes is discussed. The results of this study can be used for refining engineering procedures and processes for the manufacture of new biocompatible, bioactive, and biodegradable functional composite materials based on chitosan and synthetic polymers. 相似文献
14.
The present work focuses on the development of an in‐operando technique based on the visible spectroscopic reflectometry (VSR) for simultaneous determination of the oxide film formation during anodizing. The establishment of the VSR as in‐operando technique requires an extensive validation by comparative in‐situ but non‐operando thickness measurements under aqueous conditions. The investigations were carried out on anodic oxide films on pure titanium. The authors demonstrate the VSR as a simple and robust method for measurement under electrolyte covering. Additionally, an empirical correction algorithm extends the limitation of the visible reflectometry in thin film thickness. Reliable film thickness values can be measured down to ≥5 nm. The in‐operando mode yields additional information about the film growth time resolved. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
15.
The effect of oxygen vacancies in the anodic oxide film on passive titanium on the kinetics of the oxygen electrode reaction
has been studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Oxide films of different
donor density were prepared galvanostatically at various current densities until a potential of 20.0 VSHE was achieved. The semiconductive properties of the oxide films were characterized using EIS and Mott-Schottky analysis, and
the thickness was measured using ellipsometry. The film thickness was found to be almost constant at ∼44.7 ± 2.0 nm, but Mott-Schottky
analysis of the measured high frequency interracial capacitance showed that the donor (oxygen vacancy) density in the n-type passive film decreased sharply with increasing oxide film formation rate (current density). Passive titanium surfaces
covering a wide range of donor density were used as substrates for ascertaining relationships between the rates of oxygen
reduction/evolution and the donor density. These studies show that the rates of both reactions are higher for passive films
having higher donor densities. Possible explanations include enhancement of the conductivity of the film due to the vacancies
facilitating charge transfer and the surface oxygen vacancies acting as catalytic sites for the reactions. The possible involvement
of surface oxygen vacancies in the oxygen electrode reaction was explored by determining the kinetic order of the OER with
respect to the donor concentration. The kinetic orders were found to be greater than zero, indicating that oxygen vacancies
are involved as electrocatalytic reaction centers in both the oxygen evolution and reduction reactions.
This paper was submitted in honor of the many contributions to electrochemistry that have been made by Professor Boris Grafov.
The article is published in the original. 相似文献
16.
I. V. Lukiyanchuk L. M. Tyrina V. S. Rudnev A. Yu. Ustinov P. M. Nedozorov M. S. Vasil’eva 《Kinetics and Catalysis》2008,49(3):439-445
The possibility of the single-step formation of nickel- and copper-containing thin-film oxide systems on aluminum by plasma electrolytic oxidation was demonstrated. The resulting structures were found to be active in the reaction of CO oxidation to CO2 in the temperature region 300–500°C. However, the resulting structures exhibited stable catalytic activity only in the simultaneous presence of nickel and copper compounds. The films were studied using X-ray diffraction, X-ray spectroscopic analysis, X-ray photoelectron spectroscopy, and electron microscopy. The resulting films exhibited an essentially inhomogeneous composition through the thickness. Electrolyte elements such as nickel, copper, sodium, and phosphorus were concentrated at the surface. Nickel occurred as Ni2+, and copper occurred as Cu+ and Cu2+. The surface contained carbon in detectable amounts. 相似文献
17.
Lithium aluminates Li[Al(O-2,6-Me(2)C(6)H(3))R'(3)] (R' = Et, Ph) react with the μ(3)-alkylidyne oxoderivative ligands [{Ti(η(5)-C(5)Me(5))(μ-O)}(3)(μ(3)-CR)] [R = H (1), Me (2)] to afford the aluminum-lithium-titanium cubane complexes [{R'(3)Al(μ-O-2,6-Me(2)C(6)H(3))Li}(μ(3)-O)(3){Ti(η(5)-C(5)Me(5))}(3)(μ(3)-CR)] [R = H, R' = Et (5), Ph (7); R = Me, R' = Et (6), Ph (8)]. Complex 7 evolves with the formation of a lithium dicubane species and a Li{Al(μ-O-2,6-Me(2)C(6)H(3))Ph(3)}(2)] unit. 相似文献
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Masato Takeuchi Kouichirou Tsujimaru Kenji Sakamoto Masaya Matsuoka Hiromi Yamashita Masakazu Anpo 《Research on Chemical Intermediates》2003,29(6):619-629
Platinum-loaded titanium oxide thin-film photocatalysts were prepared by using an ionized cluster beam (ICB) deposition method and a RF magnetron sputtering (RF-MS) deposition method as dry processes. From the results of the photocatalytic oxidation of acetaldehyde with O2 under UV light irradiation, small amounts of Pt loading (less than 10 nm film thickness) were found to dramatically enhance the photocatalytic reactivity. However, when TiO2 thin films were loaded with relatively larger amounts of Pt (more than 30 nm as the film thickness), the photocatalytic reactivity became lower than for the pure TiO2 thin films. Moreover, investigations of the ratio of Pt loaded onto the surface of the thin film catalysts by XPS measurements revealed that the small amounts of Pt loaded exist as very small clusters working to efficiently enhance the charge separation, whereas, large amounts of Pt covers the entire surface of the TiO2 thin films, resulting in a decrease of the photocatalytic reactivity. 相似文献
20.
R. B. Akhverdiev I. A. Timakov R. G. Sarmurzina V. I. Yakerson M. I. Rustamov M. K. Guseinova Sh. K. Seitzhanova 《Russian Chemical Bulletin》1989,38(3):455-458
1. | Aluminum hydroxide and oxide supports, obtained by interaction with water of aluminum activated by indium or gallium, are multiphasic systems containing in the first case PB, BR, and In, and in the second, -Al2O3, In2O3, and In. |
2. | The presence of Co and Ni as alloys with activated aluminum determined the x-ray amorphous character of the Co- and Ni-containing phases at all stages, including the thermal treatment of the hydroxide and oxide systems. In the case of the copper alloy, only with thermal treatment does the partial crystallization of the CuO phase occur. |
3. | Introduction of the Co, Ni, and Cu ions into the aluminum oxide or hydroxide matrices, obtained from activated aluminum, show a definite effect on the formation of the Co3O4, CoAl2O4, and NiAl2O4 phases after thermal treatment. For the Cu-containing catalysts, the Cu2O and CuO phases are formed even before thermal treatment. |