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1.
Photocatalytic properties of porous TiO2/Ag thin films 总被引:1,自引:0,他引:1
In this study, nanocrystalline TiO2/Ag composite thin films were prepared by a sol-gel spin-coating technique. By introducing polystyrene (PS) spheres into the precursor solution, porous TiO2/Ag thin films were prepared after calcination at a temperature of 500 °C for 4 h. Three different sizes (50, 200, and 400 nm) of PS spheres were used to prepare porous TiO2 films. The as-prepared TiO2 and TiO2/Ag thin films were characterized by X-ray diffractometry (XRD) and by scanning electron microscopy to reveal structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation.When PS spheres of different sizes were introduced after calcination, the as-prepared TiO2 films exhibited different porous structures. XRD results showed that all TiO2/Ag films exhibited a major anatase phase. The photodegradation of porous TiO2 thin films prepared with 200 nm PS spheres and doped with 1 mol% Ag exhibited the best photocatalytic efficiency where ∼ 100% methylene blue was decomposed within 8 h under UV exposure. 相似文献
2.
Lanthanum lithium titanate thin films were grown by Pulsed Laser Deposition. La0.57Li0.29TiO3 dense films with smooth surfaces were obtained after optimization of the growth parameters. Such films deposited at 700 °C under 15 Pa are nano-crystalline with domains corresponding to the cubic and tetragonal modifications of this phase. In relation to the measured conductivities/activation energy and to previous works, we clearly underlined that the films of practical interest, prepared at relatively low temperature, are predominantly formed from the tetragonal ordered phase. 相似文献
3.
Angel Berenguer-Murcia Evgeny V. Rebrov Maciej Cabaj Andrew E. H. Wheatley Brian F. G. Johnson John Robertson Jaap C. Schouten 《Journal of Materials Science》2009,44(24):6563-6570
Palladium colloidal nanoparticles with an average size of approximately 2.4 nm have been incorporated into mesoporous inorganic
thin films following a multistep approach. This involves the deposition of mesoporous titania thin films with a thickness
of 200 nm by spin-coating on titanium plates with a superhydrophilic titania outer layer and activation by calcination in
a vacuum furnace at 573 K. Nanoparticles have been confined within the porous titania network by dip-coating noble metal suspensions
onto these mesoporous thin films. Finally, the resulting nanoconfined systems were used as substrates for the growth of oriented
carbon nanotubes (CNTs) using plasma-enhanced chemical vapour deposition at 923 K in order to enhance their surface area.
These CNTs were tested in the hydrogenation of phenylacetylene by hydrogen in a batch reactor. The initial reaction rate observed
on a CNT/TiO2 structured catalyst was considerably higher than that on 1 wt% Pd/TiO2 thin films. 相似文献
4.
Porous anatase (TiO2) films were fabricated onto stainless steel substrates with Ti(OC4H9)4 as a precursor via hydrothermal process. The crystallization and porous structure of TiO2 film were dependent on the time and temperature of the hydrothermal reaction. A TiO2 film with orderly porous structure and high crystallization was obtained upon treatment at 150 °C for 2 h. The grain size of TiO2 is ca. 6 nm, and pore diameter is ca. 10 nm. Diffusion of Fe into the porous TiO2 film occurred; Fe also diffused onto the surface of the film with the extension of hydrothermal reaction time or increase of the reaction temperature. The diffusion reaction has a large effect on the formation of porous TiO2 film as well as its interface texture. However, it does not change the crystal phase of the TiO2. The resultant TiO2 film showed high photocatalytic activity towards degradation of gaseous formaldehyde. 相似文献
5.
J.P. KimH.U. Lee J.E. YangJ.S. Bae E.S. ParkJ.H. Yoon J.M. KimC.R. Cho 《Thin solid films》2011,519(20):6916-6919
Dense TiO2 (D-TiO2) thin films and porous TiO2 (P-TiO2) thin films were prepared by using a polymer-blended solution. The film porosity decreased gradually or disappeared with an increase in the polyethylene glycol (PEG) or TiO2 content of the solution. To modify their surface properties, the thin films were treated with atmospheric pressure (AP) plasma by using a reactive gas. The surface morphologies of the O2-plasma-treated TiO2 (O-TiO2) thin films were smooth and did not change significantly. The decolorization efficiency of the P-TiO2 thin films was found to be enhanced when compared to that of the D-TiO2 thin films. The enhancement was due to an increase in the specific surface area and the number of hydroxyl groups, and a decrease of Ti2O3 states. 相似文献
6.
S. G. Pawar S. L. Patil M. A. Chougule B. T. Raut S. A. Pawar R. N. Mulik V. B. Patil 《Journal of Materials Science: Materials in Electronics》2012,23(1):273-279
Nanocrystalline titanium oxide thin films have been deposited by spin coating technique and then have been analyzed to test
their application in NH3 gas-sensing technology. In particular, spectrophotometric and conductivity measurements have been performed in order to determine
the optical and electrical properties of titanium oxide thin films. The structure and the morphology of such material have
been investigated by X ray diffraction, Scanning microscopy, high resolution electron microscopy and selected area electron
diffraction. The X-ray diffraction measurements confirmed that the films grown by this technique have good crystalline tetragonal
mixed anatase and rutile phase structure. The HRTEM image of TiO2 thin film showed grains of about 50–60 nm in size with aggregation of 10–15 nm crystallites. Selected area electron diffraction
pattern shows that the TiO2 films exhibited tetragonal structure. The surface morphology (SEM) of the TiO2 film showed that the nanoparticles are fine with an average grain size of about 50–60 nm. The optical band gap of TiO2 film is 3.26 eV. Gas sensing properties showed that TiO2 films were sensitive as well as fast in responding to NH3. A high sensitivity for ammonia indicates that the TiO2 films are selective for this gas. 相似文献
7.
Kelvin Y.S. Chan 《Thin solid films》2008,516(16):5582-5585
Polycrystalline Fe-doped TiO2 anatase films were deposited on (001) oriented SrTiO3 single crystal substrates at temperatures less than 200 °C from acidic aqueous solutions of titanyl sulfate and iron (III) nitrate. Epitaxial anatase TiO2 films were obtained when the films were annealed in air at 900 °C. Room-temperature ferromagnetic Fe-doped TiO2 thin films were obtained after repeated deposition and annealing steps. The observed saturation magnetization (>0.28μB/Fe) could not be attributed to the presence of secondary phase magnetic iron oxides or iron clusters. 相似文献
8.
A. H. Chiou C. G. Kuo C. H. Huang W. F. Wu C. P. Chou C. Y. Hsu 《Journal of Materials Science: Materials in Electronics》2012,23(2):589-594
Titanium dioxide (TiO2) thin films having anatase (1 0 1) crystal structure were prepared on non-alkali glass substrates by rf (13.56 MHz) magnetron
sputtering using a TiO2 ceramic target under various oxygen partial pressures. At a fixed substrate temperature of 400 °C and total gas pressure
of 1 Pa after 3 h deposition. Effects of oxygen partial pressure on the structural, surface morphology, and photocatalytic
activities of the TiO2 thin films were investigated. We performed both photoinduced decomposition of methylene blue (MB) and photoinduced hydrophilicity
under UV light illumination. The XRD patterns exhibited a broad-hump shape indicating the amorphous structure of TiO2 thin films. The results showed that when the [O2/(Ar + O2)] flow rate increased to 50%, the photoinduced decomposition of MB and photoinduced hydrophilicity were enhanced. The water
contact angle after 9 min UV illumination was approximately 4.5°, and the methylene blue (MB) solution decomposition from
12 down to 3.34 μ mol/L for 240 min UV irradiation. 相似文献
9.
Ibram Ganesh 《Materials and Manufacturing Processes》2017,32(4):431-441
Thin films of different Li2O–ZnO–Co3O4–TiO2 (LZCT) compositions were prepared and employed as electrocatalysts (i.e., anodes) to perform water oxidation reaction (WOR). The electrocatalytic activities of these thin films were compared with those exhibited by the sodium salt of cobalt phosphate (Na2CoP2O7) (CP) thin-film electrocatalyst, which is a well-known water oxidation catalyst (WOC). These results suggest that the 10Li2O–10ZnO–40Co3O4–40TiO2 composition exhibits a better catalytic activity in terms of higher faradaic efficiency (>98%), lower over potentials (<400?mV), higher reaction stability (up to 30 continuous cyclic voltammetry (CV) cycles), and the rate of O2 and H2 gas evolution in terms of current density (about 1?mA/cm2) in comparison with those exhibited by CP thin-film electrocatalyst. Furthermore, these LZCT thin films exhibited very high specific surface area values and due to the unique microstructure of ZnCo2O4 phase evolved out of these LZCT compositions at a calcination temperature of 550°C for 30?min it has been found to be responsible for the higher specific surface area values measured for these thin-film compositions. 相似文献
10.
Tong Liang 《Thin solid films》2009,517(24):6689-6693
Pb0.5Sr0.5TiO3 thin films were prepared on Pt/TiO2/SiO2/Si and LaNiO3 (LNO)/Si substrates by using chemical solution deposition technique, and a layer-by-layer annealing method was used in an attempt to improve the dielectric properties of the thin films. The structure, dielectric, and ferroelectric properties of the thin films were investigated. Improved dielectric properties of the thin films were clearly confirmed: the dielectric constant and dielectric loss for the films on Pt/TiO2/SiO2/Si substrates annealed at 650 °C were 1064 and 0.027, respectively, at 1 kHz, with a dielectric tunability of more than 50%; similarly, the films prepared on LNO/Si substrates, showed a high dielectric constant of 1280 and a low dielectric loss of 0.023, at 1 kHz. P-E hysteresis loop measurements indicated that the remanent polarization and coercive field for the films on Pt/TiO2/SiO2/Si substrates annealed at 650 °C were 15.7 μC/cm2 and 51 kV/cm, respectively. 相似文献
11.
Ag-TiO2 nanostructured thin films with silver volume fraction of 0–40% were prepared by RF magnetron sputtering. The microstructure, surface topography, and optical properties of the films were characterized by X-ray diffractometer, transmission electron microscope, and ultraviolet–visible spectrophotometer. Photocatalytic activity of the films was evaluated by light-induced degradation of methyl orange (C14H14N3NaO3S) solution using a high pressure mercury lamp as lamp-house. The relation of photocatalytic activity and silver content was studied in detail. It is found that silver content influences microstructure of TiO2 thin films, and silver in the films is metallic Ag (Ag0). Photocatalytic activity of the films increases with increasing silver content up to 5 vol.% Ag and then decreases to values significantly still bigger than that of pure TiO2 thin films. Silver nanoparticles significantly enhance the photocatalytic activity of TiO2 films. The better separation between electrons and holes on silver modified TiO2 thin films surface allowed more efficiency for the oxidation and reduction reactions. The enhanced photocatalytic activity was mainly attributed to the decrease of energy gap of the films and the increase of oxygen anion radicals O2− and reactive center of surface Ti3+ on silver modified TiO2 thin films surface. 相似文献
12.
Ordered porous TiO2 thin films were fabricated on conductive glass by using colloid crystal template of polystyrene (PS) spheres. Microstructural characterization by scanning electron microscopy techniques was carried out to explore the porous structural changes due to the PS templates which could be controlled by adjusting the drawing rate. Photovoltaic performance was measured and this revealed the effect of microstructural changes. The results showed that monolayer porous TiO2 films and multilayer porous TiO2 films could be successfully prepared. And multilayer porous TiO2 films provided large surface area for dye absorption to increase the efficiency of dye-sensitized solar cells (DSSCs) which were assembled by porous TiO2 films. 相似文献
13.
Ibram Ganesh A.K. GuptaP.P. Kumar P.S. Chandra SekharK. Radha G. PadmanabhamG. Sundararajan 《Materials Chemistry and Physics》2012
Different amounts of Co-doped TiO2 powders and thin films were prepared by following a conventional co-precipitation and sol–gel dip coating technique, respectively. The synthesized powders and thin films were subjected to thermal treatments from 400 to 800 °C and were thoroughly investigated by means of X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive analysis with X-rays, FT-infrared, FT-Raman, diffuse reflectance spectroscopy, ultraviolet–visible spectroscopy, BET surface area, zeta potential, flat band potential measurements, band-gap energy, etc. The photocatalytic ability of the powders was evaluated by methylene blue (MB) degradation studies. The thin films were characterized by photocurrent and ultraviolet–visible (UV–Vis) spectroscopy techniques. The characterization results suggest that the Co-doped TiO2 powders synthesized in this study consist mainly anatase phase, and possess reasonably high specific surface area, low band gap energy and flat band potentials amenable to water oxidation in photoelectrochemical (PEC) cells. The photocatalytic degradation of MB over Co-doped TiO2 powders followed the Langmuir–Hinshelwood first order reaction rate relationship. The 0.1 wt.% Co-doped TiO2 composition provided the higher photocurrent, n-type semi-conducting behavior and higher photocatalytic activity among various Co-doped TiO2 compositions and pure TiO2 investigated. 相似文献
14.
Microstructure and hydrophilicity of nano-titanium dioxide (TiO2) thin films, deposited by radio frequency magnetron sputtering, annealed at different temperatures, were studied by field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and water contact angle methods. It is found that the crystal phase transforms from amorphous to rutile structure with increase of annealing temperature from room temperature to 800 °C. It is also indicated that the organic contaminants on the surface of the films can be removed and the oxygen vacancies can be reduced by the annealing treatment. Annealed at the temperature below 300 °C, amorphous TiO2 thin films show rather poor hydrophilicity, and annealed at the temperature range from 400 to 650 °C, the super hydrophilicity anatase of TiO2 thin films can be observed. However, when the annealing temperature reaches 800 °C, the hydrophilicity of the films declines mainly derived from the appearance of rutile. 相似文献
15.
When colloidal crystal films are deposited onto nanocrystalline porous substrates by the commonly used colloidal crystallization method of vertical deposition self-assembly, the colloidal crystal tends to be poorly adhered to the porous film. Herein, we present a fabrication of large-area, three-dimensional (3D) colloidal crystal thin films on nanocrystalline porous substrates by a room temperature floating self-assembly method that has recently been developed for colloidal crystal deposition. Firstly, colloidal suspensions were prepared by dispersing monodisperse colloidal microspheres at high volume fraction in a mixture of ethanol and water. At room temperature, these suspensions were spread onto nanocrystalline porous TiO2 films. The colloidal particles assembled into 3D ordered structures at the air−liquid interface of the suspensions as a result of rapid evaporation of the solvents. After the solvents (water and ethanol) had evaporated completely, the colloidal crystals were directly deposited on the nanocrystalline porous TiO2 films. Scanning electron microscopy images and normal-incidence transmission spectra of the samples showed that the colloidal crystal films deposited on the nanocrystalline porous TiO2 substrates by this method had very high crystalline quality. In addition, the effect of the degree of surface roughness of the nanocrystalline porous substrate on the crystalline quality of the colloidal crystals has been studied. 相似文献
16.
Gustav Plesch Michal Gorbár Ulrich F. Vogt Karol Jesenák Melinda Vargová 《Materials Letters》2009,63(3-4):461-463
Ceramic macroporous reticular alumina foams with a pore size of 15, 20 and 25 pores per inch (ppi) were prepared by the Schwartzwalder method and sintered at 1200 °C to preserve a high porosity. TiO2 thick films were supported on the foam surface by a wash coating process, using Degussa P25 as a TiO2 nanopowder source. After annealing at 600 °C, films with an adequate adhesion and with a thickness of 5–10 μm were obtained. An increasing pore size of the supported foams improves the specific photocatalytic activity of the TiO2 coated scaffolds, the flow of solution through the highly active porous foam structure and the better access of light to the active TiO2 surface. 相似文献
17.
Byeong-Eog Jun Hui-Jin Park Hyun-Kyoung Yang Byung-Chun Choi Jung-Hyun Jeong 《Thin solid films》2008,516(16):5266-5271
Li doped zinc oxide Zn1−xLixO (x = 0.15) thin films were grown by using the pulsed laser deposition method. The depositions were done onto Pt(111)/Ti/SiO2/Si(100) substrate set at temperatures ranging from 300 °C to 700 °C, with varying the ambient O2 pressure range of 3-20 mTorr. The effects of substrate temperatures and ambient O2 pressures on the surface morphology and structural properties of the Zn0.85Li0.15O thin films were investigated by using the scanning probe microscopy and X-ray diffraction spectra, respectively. Also the chemical structures of the films were investigated by observing the X-ray photoelectron spectra of the core and shallower levels. We observed the deep blue PL emissions centered at about 390 nm (3.20 eV) from the Zn0.85Li0.15O thin films. It was investigated with respect to the ambient O2 pressures during the deposition. It is considered that the deep blue PL emission in the Zn0.85Li0.15O thin film may be related to the incorporation of oxygen vacancies. 相似文献
18.
《Thin solid films》2006,494(1-2):228-233
TiO2 materials possessing not only photocatalytic but also electrochromic properties have attracted many research and development interests. Though WO3 exhibits excellent electrochromic properties, the much higher cost and water-sensitivity of WO3 as compared with the TiO2 may restrict the practical application of WO3 materials. In the present study, the feasibility of preparing nanocrystalline porous TiO2/WO3 composite thin films was investigated.Precursors of sols TiO2 and/or WO3 and polystyrene microspheres were used to prepare nanocrystalline pure TiO2, WO3, and composite TiO2/WO3 thin films by spin coating. The spin-coated thin films were amorphous and, after heat treating at a temperature of 500 °C, nanocrystalline TiO2, TiO2/WO3, and WO3 thin films with or without pores were prepared successfully. The heat-treated thin films were colorless and coloration-bleaching phenomena can be observed during cyclic voltammetry tests. The heat-treated thin films exhibited good reversible electrochromic behavior while the porous TiO2/WO3 composite film exhibited improved electrochromic properties. 相似文献
19.
M. Ueda M. Ikeda M. Ogawa 《Materials science & engineering. C, Materials for biological applications》2009,29(3):994-1000
The chemical–hydrothermal combined synthesis of TiO2 and CaTiO3 films on pure Ti substrates was examined with a focus on crystallinity and surface morphology of the films. Pure Ti disks were chemically treated with H2O2/HNO3 solutions at 353 K for 5–60 min in order to introduce a TiO2 layer with low crystallinity on the surface. The samples were then hydrothermally treated in an autoclave at 453 K for 12 h. Anatase-type TiO2 and perovskite-type CaTiO3 films with high crystallinity were obtained upon treatment with distilled water and an aqueous solution of Ca(OH)2, respectively. Cracks in the TiO2 precursor films disappeared after hydrothermal treatment. Uniform and crack-free films could be obtained by the present process. In addition, in vitro formation of hydroxyapatite (HAp) on the films was investigated. Obtained samples were immersed in SBF (Simulated Body Fluid), adjusted to 310 K. A light HAp precipitate could be observed on non-surface modified Ti after 6 days of immersion. In contrast, precipitate formed after only 2 days on the present oxide films. The present surface modification was confirmed to drastically promote deposition of HAp on the surface of Ti. 相似文献
20.
The surfactant effect of Ag on the thin film structure of TiO2 by radio frequency magnetron sputtering has been investigated. Comparisons between the atomic force microscopy images revealed that the surface roughness of TiO2 film mediated by Ag was smaller than that of the TiO2 film without Ag. The surface segregation effect of Ag was confirmed using X-ray photoelectron spectroscopy. The results of X-ray diffraction revealed that the initial deposition of a 0.4 nm thick Ag surfactant layer onto a Fe buffer layer prior to the deposition of the TiO2 film reduced the rutile (110) growth and enhanced the anatase (100) growth. It was concluded that Ag was an effective surfactant for changing the thin film structure of TiO2 on the Fe buffer layer. The photocatalytic effect of the fabricated TiO2 film was also investigated using the remote oxidation process. TiO2 films with the Ag surfactant exhibited higher photocatalytic activity than conventionally deposited TiO2 films. 相似文献