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1.
Mesoporous TiO 2 films were prepared by using titanium tetraisopropoxide as the titania precursor and triblock copolymer as the structure directing agent. The synthesized mesoporous TiO 2 film was confirmed to have the ordered pore structure with rutile phase by small angle and wide angle X-ray diffraction analyses. The mesoporous TiO 2 film has the porosity range from 21.6 to 35.6%, and its Seebeck coefficient was changed according to its porosity, up to −88.6 μV/K. From the obtained Seebeck coefficient, the ordered mesoporous TiO 2 film was found to be a good candidate of thermal sensing layer of thin film thermal sensor. 相似文献
2.
Coatings, comprising an inner porous anodic alumina film and an outer polyaniline/TiO 2 nanoparticle layer, were electrochemically synthesised on an AA2024-T3 aluminium alloy by single-step, anodic polarisation in an oxalic acid-based electrolyte. The morphology and composition of the coatings were examined by TEM, SEM and XPS, with the size and zeta-potential of the TiO 2 nanoparticles in the oxalic acid solution also measured. Observation of the growth of the coating during of anodic polarisation revealed that a distinct, two-layered coating is formed from the early stages of polarisation, with the anodic film forming at a constant rate and the outer layer developing at a rate that decreases markedly with times beyond about 30 min. Nanoparticles, agglomerated in the electrolyte, migrate to the anode due to the negative zeta-potential and form the nanoparticle-containing layer at the surface of anodic film. Such particles are not incorporated in the pores due to agglomeration and disordered film porosity at the outer layer of the anodic film. 相似文献
3.
The sub-micron size anatase TiO 2 particles with size about 0.2-0.3 μm were synthesized with basic peptizing agent and hydrothermal method and added into TiO 2 film as light scattering center. The addition of the sub-micron size anatase TiO 2 particles enhanced light scattering and dye adsorption abilities of the TiO 2 film. When the weight proportion of the sub-micron size/nano-size TiO 2 particles in the TiO 2 film attained to 1.25/10, the highest energy conversion efficiency about 7.41% was obtained, which was 23% enhancement comparing
with the TiO 2 film containing pure nano-size TiO 2 particles. It presented an efficient way for improving the photovoltaic performance of dye-sensitized solar cell. 相似文献
4.
High density TiO 2 nanotube film with hexagonal shape and narrow size distribution was fabricated by templating ZnO nanorod array film and sol-gel process. Well-aligned ZnO nanorod array films obtained by aqueous solution method were used as template to synthesize ZnO/TiO 2 core-shell structure through sol-gel process. Subsequently, TiO 2 nanotube array films survived by removing the ZnO nanorod cores using wet-chemical etching. Polycrystalline anatase TiO 2 nanotube films were ∼ 1.5 μm long and ∼ 100 nm in inter diameter with a wall thickness of ∼ 10 nm. 相似文献
5.
Micro-arc oxidation method is a useful process for mesoporous titanium dioxide films. In order to improve the photocatalytic activity of the TiO 2 film, N-Eu co-doped titania catalyst was synthesized by micro-arc oxidation in the H 2SO 4/Eu(NO 3) 3 mixture solution.The specific surface area and the roughness of the anodic titania film fabricated in the H 2SO 4/Eu(NO 3) 3 electrolyte, were increased compared to that of the anodic TiO 2 film prepared in H 2SO 4 solution. The absorbance response of N-Eu titania film shows a higher adsorption onset toward visible light region, and the incorporated N and Eu ions during anodization as a dopant in the anodic TiO 2 film significantly enhanced the photocatalytic activity for dye degradation. After dye decomposition test for 3 h, dye removal rates for the anodic TiO 2 film were 60.7% and 90.1% for the N-Eu doped titania film. The improvement of the photocatalytic activity was ascribed to the synergistic effects of the surface enlargement and the new electronic state of the TiO 2 band gap by N and Eu co-doping. 相似文献
6.
Porous anatase (TiO 2) films were fabricated onto stainless steel substrates with Ti(OC 4H 9) 4 as a precursor via hydrothermal process. The crystallization and porous structure of TiO 2 film were dependent on the time and temperature of the hydrothermal reaction. A TiO 2 film with orderly porous structure and high crystallization was obtained upon treatment at 150 °C for 2 h. The grain size of TiO 2 is ca. 6 nm, and pore diameter is ca. 10 nm. Diffusion of Fe into the porous TiO 2 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 TiO 2 film as well as its interface texture. However, it does not change the crystal phase of the TiO 2. The resultant TiO 2 film showed high photocatalytic activity towards degradation of gaseous formaldehyde. 相似文献
7.
3-(2-benzothiazolyl)-7- N, N-diethylaminocoumarin organic laser dye-polymethyl methacrylate (PMMA) composite films doped with inorganic titanium dioxide (TiO 2) particles are fabricated by spin-coating technique. TiO 2 nanoparticles exhibit a strong influence on optical properties of the organic laser dye/PMMA composite films. The refractive index and absorbance (absorption intensity) of organic laser dye/PMMA composite film with micro- and nanoparticles of TiO 2 are reduced, compared to those without TiO 2 particles. The organic laser dye/PMMA composite film with TiO 2 nanoparticles has the lowest refractive index and absorbance values. Photoluminescence intensities of all systems exhibit a maximum peak around the excitation wavelength, close to that of the organic laser dye, at 450 nm and the minimum around the excitation wavelength of 350 nm. Photoluminescence intensity of the organic laser dye/PMMA composite film with TiO 2 microparticles is always the lowest at all excitation wavelengths. However, the photoluminescence intensity of the organic laser dye/PMMA composite film with TiO 2 nanoparticles has the highest value at excitation wavelengths of 330 and 380 nm, while the photoluminescence intensity of composite film without TiO 2 particles is more than that with nanoparticles at other excitation wavelengths. 相似文献
8.
The surface morphology of titanium oxide (TiO 2) films as a photoanode in dye sensitized solar cells plays a vital role in converting light to electricity. Therefore, TiO 2 films were prepared using TiO 2 paste with different compositions of poly(vinylpyrrolidone) (PVP) as a binder to optimize their physico-chemical properties. The paste was prepared with commercial TiO 2 powder mixed with acetylacetone, PVP, 4-octylphenol polyethoxylate, acetic acid and ethanol. The chemical composition remains the same for all pastes except PVP. The quantity of the PVP was optimized in such a way that it provides a thick film with a good network connection. The impact of the quantity of PVP in the TiO 2 paste was analyzed. The prepared TiO 2 film structure was characterized by X-ray diffraction. The surface morphology was analyzed by scanning electron microscopy. The electrochemical performance of the prepared TiO 2 as a photoanode was also investigated. Among the four different photoanodes, the cells fabricated with a TiO 2 film prepared with 0.4 g of PVP exhibited the highest power conversion efficiency of 6.77%, short-circuit photocurrent density and open circuit voltage of 12.38 mA/cm 2 and 0.77 V, respectively. 相似文献
9.
Platinized catalysts on various types of supports were tested in the catalytic decomposition of hydrazine in HClO 4 and HNO 3 solutions, where the process follows different pathways. In HClO 4, the activity of the catalysts supported on a Termoksid ceramic material is higher than that of the catalysts supported on amorphous silica gel. In nitric acid solutions, the trend is reverse. Peptization of the ceramic supports in acid solutions increasing in the order 75% TiO 2-25% SnO 2 < 75% TiO 2-25% ZrO 2 ? TiO 2 < ZrO 2 was observed. In perchloric acid solutions, the catalyst specific activity in the hydrazine adsorption-dissociative decomposition increases with decreasing size of platinum crystallites on the support. In nitric acid solutions, where the hydrazine decomposition proceeds as its catalytic oxidation with nitric acid, the catalyst specific activity decreases with a decrease in the size of the catalyst crystallites, i.e., the catalyst centers located on large crystallites are more active. The results obtained were attributed to the energetic heterogeneity of the surface Pt atoms and various mechanisms of the hydrazine catalytic decomposition in various media. 相似文献
10.
In this paper, Cu 2O was studied as a photon absorber for solar cell applications. Cu 2O was deposited on a TiO 2 film using the electrochemical deposition (ECD) method. Based on the physical appearance of the samples, the particles of Cu 2O seemed to penetrate the TiO 2 film and were primarily deposited near the TiO 2/substrate interface rather than on the TiO 2 film surface. This method could be one way to generate a p-n bulk-heterojunction interface. The film was confirmed to be a Cu 2O/TiO 2 composite via X-ray diffraction measurements. The top electrode was formed by evaporating indium for I-V characterization, and the fabricated cell showed photovoltaic properties. 相似文献
11.
Anodized TiO 2 nanotube arrays fabricated on a TiO 2 thin film on conducting glass substrates can be readily implemented in diverse applications like hybrid solar cells. In this study, we concentrate on morphologies with inner tube diameter being around 30 nm which is in dimension of the exciton diffusion length of common organic hole conductors. Cross-sectional preparation of the intact tube array in correlation with transmission electron microscopy has been performed to get local information on the TiO 2 nanotubes and their arrangements, depending on anodization voltage. Crystallites have been found to be anatase and in size of several hundred nanometers along tube walls with increasing length for increasing anodization voltages. Inter-tube connections with similar crystal orientations of adjacent tubes are found. These give rise to large areas of uniform orientation. Thus, the number of grain boundaries within the film is low compared to the reported values for different TiO 2-polymer material systems. Using the arrays, hybrid TiO 2 solar cells were fabricated, which show high fill factors indicating good electron transport. The results suggest high electron mobility and are encouraging for a utilization of the nanotube arrays in next generation photovoltaics. 相似文献
12.
A transparent, high purity titanium dioxide thin film composed of densely packed nanometer sized grains has been successfully
deposited on a glass substrate at 30°C from an aqueous solution of TiO 2-HF with the addition of boric acid as a scavenger by liquid phase deposition technique. From X-ray diffraction measurement,
the deposited film was found to be amorphous and turns crystalline at 500°C. The deposited film showed excellent adherence
to the substrate and was characterized by homogeneous flat surface. TiO 2 thin films can be used as a photocatalyst to clean up organohalides, a class of compound in pesticides that pollute the ground
water. Photocatalytic degradation experiments show that indanthrene golden orange dye undergoes degradation efficiently in
presence of TiO 2 thin films by exposing its aqueous solution to ultraviolet light. The suitable surface structure and porosity increases the
photocatalytic activity. It was also observed that hemin doped TiO 2 thin films break up organohalides at a surprisingly high rate under visible light. 相似文献
13.
The surfactant effect of Ag on the thin film structure of TiO 2 by radio frequency magnetron sputtering has been investigated. Comparisons between the atomic force microscopy images revealed that the surface roughness of TiO 2 film mediated by Ag was smaller than that of the TiO 2 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 TiO 2 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 TiO 2 on the Fe buffer layer. The photocatalytic effect of the fabricated TiO 2 film was also investigated using the remote oxidation process. TiO 2 films with the Ag surfactant exhibited higher photocatalytic activity than conventionally deposited TiO 2 films. 相似文献
14.
The surfactant effect of Ag on the thin film structure of TiO 2 by radio frequency magnetron sputtering has been investigated. Comparisons between the atomic force microscopy images revealed that the surface roughness of TiO 2 film mediated by Ag was smaller than that of the TiO 2 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 TiO 2 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 TiO 2 on the Fe buffer layer. The photocatalytic effect of the fabricated TiO 2 film was also investigated using the remote oxidation process. TiO 2 films with the Ag surfactant exhibited higher photocatalytic activity than conventionally deposited TiO 2 films. 相似文献
15.
TiO2 film modified by Bi2O3 microgrid array was successfully fabricated by using a microsphere lithography method.The structure and morphology of TiO2 film,Bi2O3 film and TiO2 film/Bi2O3 microgrid heterojunction were characterized through X-ray diffraction,atomic force microscopy and scanning electron microscopy.The optical transmittance spectra and the photocatalytic degradation capacity of these samples to rhodamine B were determined via ultraviolet-visible spectroscopy.The results indicated that the coupled system showed higher photocatalytic activity than pure TiO2 and Bi2O3 films under xenon lamp irradiation.The enhancement of the photocatalytic activity was ascribed to the special structure,which could improve the separation of photo-generated electrons and holes,enlarge the surface area and extend the response range of TiO2 film from ultraviolet to visible region. 相似文献
16.
In this paper, the TiO 2/HS-CH 2-COOH/Cu 3Se 2 composite film photoanodes were fabricated on conducting glass plates. Cu 3Se 2 nanoparticles were used as the sensitizer and the bi-functional modifier HS-CH 2-COOH was used at the interface between Cu 3Se 2 and TiO 2 films to improve the properties of the film photoanode. The characterization results show that the sol-gel prepared anatase TiO 2 film has a compact and uniform surface, while the tetragonal Cu 3Se 2 film has a coarse surface which is made up of uniform elongated particles. The photoelectrochemical experimental results indicate that the TiO 2/HS-CH 2-COOH/Cu 3Se 2 composite film photoanodes have a good photovoltaic property. 相似文献
17.
Porous TiO 2 films with both mesoporosity and macroporosity were fabricated by a templated sol–gel method for applications, such as dye-sensitized solar cells (DSC), photocatalysis and catalysis. With the incorporation of differently sized pores, the resultant structures exhibit high surface areas and possess interpenetrating aligned pore channels, which are believed to be beneficial for applications where diffusion of reactants to interior surface can be rate limiting. Both liquid and solid TiO 2 precursors can be applied for large area coating in this process. Almost crack-free films were produced by templated coating of pre-synthesized TiO 2 nanoparticles. The measured specific surface area and porosity of synthesized films were in the range of 33–137 m 2/g and 61–80%, respectively, depending on the size of the selected template. 相似文献
18.
Highly porous and well interconnected titanium dioxide (TiO 2) scaffolds with compressive strength above 2.5 MPa were fabricated without compromising the desired pore architectural characteristics,
such as high porosity, appropriate pore size, surface-to-volume ratio, and interconnectivity. Processing parameters and pore
architectural characteristics were investigated in order to identify the key processing steps and morphological properties
that contributed to the enhanced strength of the scaffolds. Cleaning of the TiO 2 raw powder removed phosphates but introduced sodium into the powder, which was suggested to decrease the slurry stability.
Strong correlation was found between compressive strength and both replication times and solid content in the ceramic slurry.
Increase in the solid content resulted in more favourable sponge loading, which was achieved due to the more suitable rheological
properties of the ceramic slurry. Repeated replication process induced only negligible changes in the pore architectural parameters
indicating a reduced flaw size in the scaffold struts. The fabricated TiO 2 scaffolds show great promise as load-bearing bone scaffolds for applications where moderate mechanical support is required. 相似文献
19.
New processes for the preparation of nanostructure on glass surfaces have been developed through anodic oxidation of sputtered aluminum. Aluminum thin film sputtered on a tin doped indium oxide (ITO) thin film on a glass surface was converted into alumina by anodic oxidation. The anodic alumina gave nanometer size pore array standing vertically on the glass surface. Kinds of acids used in the anodic oxidation changed the pore size drastically. The employment of phosphoric acid solution gave several tens nanometer size pores. Oxalic acid cases produced a few tens nanometer size pores and sulfuric acid solution provided a few nanometer size pores. The number of pores in a unit area could be changed with varying the applied voltage in the anodization and the pore sizes could be increased by phosphoric acid etching. The specimen consisting of a glass substrate with the alumina nanostructures on the surface could transmit UV and visible light. An etched specimen was dipped in a TiO 2 sol solution, resulting in the impregnation of TiO 2 sol into the pores of alumina layer. The TiO 2 sol was heated at ∼400 °C for 2 h, converting into anatase phase TiO 2. The specimens possessing TiO 2 film on the pore wall were transparent to the light in UV–Visible region. The electro deposition technique was applied to the introduction of Ni metal into pores, giving Ni nanorod array on the glass surface. The removal of the barrier layer alumina at the bottom of the pores was necessary to attain smooth electro deposition of Ni. The photo catalytic function of the specimens possessing TiO 2 nanotube array was investigated in the decomposition of acetaldehyde gas under the irradiation of UV light, showing that the rate of the decomposition was quite large. 相似文献
20.
Herein, titanium dioxide (TiO2)-coated vertically aligned silicon nanowires (SiNWs/TiO2) were fabricated and evaluated for photocatalytic degradation of organic dyes. Aligned SiNWs arrays were prepared by facile metal-assisted chemical-etching process with varying the etching time that was followed by TiO2 nanoparticles coating using sputtering technique. The TiO2 film crystallized in pure anatase phase with an average crystalline size of 50 nm, as was elucidated with X-ray diffraction studies. SEM analysis showed nanowires with varying lengths from 2.5 to 13.5 µm and confirmed the homogenous surface decoration with TiO2. The homogeneous distribution of TiO2 nanoparticles on nanowires was co-evidenced with Energy-Dispersive X-ray spectroscopy (EDX) and Raman spectra analysis. The developed SiNWs/TiO2 was exploited for photocatalytic degradation of methylene blue; the role of hydrogen peroxide was also elucidated. The highest photocatalytic efficiency of 96% was achieved for SiNWs/TiO2 with optimum nanowire length of 3.5 μm. The developed photocatalyst was found to be almost stable even after 190 days (~?5 months) and could be used as reusable and easily removable photocatalysts. The current study highlighted the SiNWs/TiO2/H2O2 system as excellent candidate for water remediation applications. 相似文献
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