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1.
Titania thin films with various nanostructures of quasi-aligned nanorods, well-aligned nanotubes and nanoparticle aggregates were fabricated and utilized to assist photodegradation of three typical dye derivatives in water, i. e., rhodamine B (RB), methylene blue (MB) and methyl orange (MO). The thin films were characterized by X-ray diffraction, scanning electron microscope and UV-Vis diffuse reflectance spectra. It is found that the bandgap of most lab-fabricated thin films can be estimated more appropriately assuming a direct transition between the valance band and the conduction band of titania. The so-called natural ageing phenomenon was evidence for all the films to assist photodegradation of RB and MB in water; but not discernible for MO, which was much reluctant to photodegradation. MB decomposed much quickly than RB when assisted by titania with predominantly anatase; on the other hand, rutile favored the photodegradation of RB than that of MB. Titania thin films with top morphologies of quasi-aligned nanorods or nanotubes were found to possess advantageous turnover frequency and photonic efficiency over commercial P25 titania and sol-gel derived titania to assist photodegradation of RB and MB in water. 相似文献
2.
Photocatalytic performance of Gd ion modified titania porous hollow spheres under visible light 总被引:1,自引:0,他引:1
In this work, Gd-doped titania hollow spheres were prepared using hydrothermally prepared carbon spheres as template. The prepared samples were characterized by XRD, TEM, SEM, DRS and XPS. The photocatalytic activity of as-prepared hollow titania spheres was determined by degradation of Reactive Brilliant Red dye X-3B (C.I. reactive red 2) under visible light irradiation. The effect of Gd content on the physical structure and photocatalytic properties of doped titania hollow sphere samples was investigated. Results showed that there was an optimal Gd-doped content (4%) for the photocatalytic activity of X-3B degradation. 相似文献
3.
Oriented rutile nanorod arrays are precipitated on metallic Ti plates from a precursor derived by interactions between Ti and aqueous hydrogen peroxide. Pulsed laser deposition (PLD) is then carried out to deposit titania on the nanorod arrays, in comparison with bare Ti substrates, utilizing a high-temperature sintered rutile target in oxygen atmosphere. It is found that dense and homogeneous titania thin films are obtained on Ti substrates; while growth on the rutile nanorod arrays is epitaxial, resulting in enlarged nanorods conformally covered with titania. Titania grown on both Ti substrates and rutile nanorod arrays is either pure rutile or a mixture of anatase and rutile, with the formation of anatase favored by an increasing oxygen pressure during the PLD procedure. The surface roughness and the particle size of the dense titania films on Ti substrates increase as a result of increasing oxygen pressure and prolonged deposition time. The PLD-induced epitaxial growth of titania is inhibited by increasing substrate temperatures. The photocatalytic experiments reveal a significantly enhanced activity for the rutile nanorod arrays after a subsequent PLD treatment. 相似文献
4.
In order to study the microstructure of cadmium telluride (CdTe) photovoltaic thin film solar cells, manufactured by an in-line manufacturing process, Scanning Electron Microscopy characterization (SEM) and X-ray diffraction (XRD) characterization were performed. SEM measurement showed that no substantial changes in the grain structure of CdTe layers occurred during the Cadmium Chloride (CdCl2) treatment. No change in the cubic CdTe lattice parameter “a” was observed for the CdCl2 treated sample. It is inferred that the primary effect of the CdCl2 treatment in the devices studied is the passivation of grain boundaries and bulk defects. XRD studies show a loss of preferred orientation (as determined from the peak ratios) of planes during the copper compound treatment indicating recrystallization of the grains due to the Cu treatment. Also the Cu treated sample showed decrease in value of the lattice parameter “a”. 相似文献
5.
Mesoporous vanadium pentoxide (V2O5) films have been synthesized by hydrolysis of vanadium tri-isopropoxide (VO(OC3H7)3) in the presence of polyethylene glycol (PEG) as a structure-directing agent. The structure, the stoichiometry and the morphology of the films have been studied as a function of the thermal annealing by X-ray diffraction (XRD), micro-Raman spectroscopy, optical microscopy, scanning electron microscopy and atomic force microscopy. XRD patterns and Raman spectra show the presence of two previously unreported crystalline phases. The PEG:V2O5 molar ratio affects the temperature of phase formation, the amount and even the order in which the phases appear. The morphological characterization underlines the role of the surfactant to promote porous networks, formed by micrometric clusters of controlled shapes and patterns embedded in a homogeneous host matrix. 相似文献
6.
J. Luschitz 《Thin solid films》2007,515(15):5814-5818
We have systematically investigated the growth of CdTe thin films by Close Spaced Sublimation (CSS). Thin films of CdTe were deposited onto CdS substrates held at temperatures in the range 250 to 550 °C. The effect of substrate temperature and evaporation rate on structure and surface morphology of CdTe films were investigated. Up to 450 °C substrate temperature the growth rate was almost constant and decreased exponentially for higher temperatures. The structures of the CdTe films were determined by XRD and a strong (111) orientation was observed within the temperature range 250 °C-470 °C. Above 470 °C the texture changed to mostly (311) and (220) orientations. Surface morphology and grain size of CdTe growth was determined with AFM and SEM. The morphology of the layers showed three major modes: Columnar grains with a diameter of 0.2 μm and a length of 6 μm for temperatures from 250 °C to 350 °C, pyramidal grains with a diameter of 0.5-1.5 μm up to 470°C and irregular shaped grains with a diameter of 5-10 μm for temperatures up to 550 °C. The roughness increased linearly from 15 nm to 220 nm within the substrate temperature range. 相似文献
7.
Songwang Yang 《Materials Research Bulletin》2008,43(7):1872-1876
This work provides the design and synthesis of nitrogen doped rutile TiO2 nanoparticles working as efficient photocatalysts under visible light irradiation. Nitrogen doped rutile TiO2 nanoparticles are synthesized through the surface nitridation of rutile nanoparticles, which have been prepared in advance. The experimental results show that the nitrogen element is easily doped into the lattice of TiO2 nanoparticles and its doping amount increases with the decrease of nanocrystallite size. The photocatalytic activity of the nanoparticles under visible light irradiation is correlated not only with the amount of doped nitrogen element but also with the morphology and crystallinity of nanoparticles. 相似文献
8.
Ekoko Bakambo Gracien Jianian Shen XianRong Sun Dong Liu Moucheng Li ShuDian Yao Juan Sun 《Thin solid films》2007,515(13):5287-5297
Transition metal-doped TiO2 electrodes were prepared by re-anodization and characterized. The structure of these electrodes was investigated by X-ray diffraction and electron diffraction, which mainly showed typical characteristic anatase reflections without any dopant-related peaks. The amount of transition metal dopant in TiO2 was kept at approximately 1.0 at.%, as measured by energy dispersive X-ray spectroscopy. The effects of different types of dopants on the photocatalytic activity were revealed by measuring the degradation of an organic aqueous solution containing a dye (acid red G) using a combination of ultraviolet (UV) light energy in the presence of these electrodes. The photocatalytic efficiency was remarkably enhanced by the incorporation of Mn 2+ and Cr3+. Mn2+ showed the most significant enhancement. However, Co2+ accelerated the rate of acid red G degradation only slightly. Langmuir-Hinshelwood rate expression was employed for the degradation of acid red G by UV/TiO2 electrodes system. The adsorption equilibrium constant, the rate constant, and the initial degradation rate were determined for different electrodes. The effect of the concentration of Mn2+ on the degradation of acid red G was also investigated and the results showed that there is an optimal value (about 1.0 at.%) of the concentration of Mn2+ for inducing faster degradation of the dye. The enhanced photocatalytic degradation rate of acid red G in the presence of transition metals is attributed to the increase of the charge separation in these systems. 相似文献
9.
Titanium carbide (TiC) coatings for tribological applications were deposited on high speed steel. Several coatings with different titanium to carbon ratio were deposited by means of physical vapour deposition in which titanium was evaporated and carbon was sputtered. The coatings were characterised using analytical electron microscopy. It was observed that the change in titanium to carbon ratio significantly changed the microstructure of the coatings. The low carbon containing coatings consisted of columnar grains exhibiting a preferred crystallographic orientation whereas the coating with highest carbon content consisted of randomly ordered TiC grains in an amorphous carbon matrix. Energy filtered transmission electron microscopy revealed a change in Ti/C ratio as the distance from the substrate increased. The titanium to carbon ratio was observed to increase with distance from the substrate until a stable level was reached. This is due to a variation in the titanium evaporation during the early stages of film growth. This change of the titanium to carbon ratio affected the columnar growth in the initial stage of coating growth for the coatings with low carbon content. 相似文献
10.
Titanium dioxide is one of the most commonly used semiconductors for photocatalytic applications. In the majority of experimental studies, titanium dioxide is used in a powder form. In the present investigations titanium dioxide layers were formed by the plasma assisted anodic oxidation process SOLECTRO®. In this process a titanium substrate (anode) is dipped into an electrolyte bath containing a titanium precursor. Impressing a voltage greater than 100 V, a titanium dioxide layer is deposited on the substrate in several minutes. The titanium dioxide is formed from the constituents of the electrolyte. For this reason, the composition of the electrolyte influences the deposition process and also the phase fractions and the layer morphology. It is known that the photocatalytic activity of titanium dioxide layers depends strongly on the anatase volume fraction, the layer morphology and therefore the specific surface area. The standard SOLECTRO® process generates titanium dioxide layers consisting of nearly 25 vol.% anatase and 75 vol.% rutile. In the present study, the electrolyte's constituents, especially the chelating agent, were varied to increase the anatase percentage. The results show that the anatase fraction and the specific surface area can be increased by substitution of ethylendiammintetraacetic acid by dieethylenetriaminepentaacetic acid. The anatase fraction amounts to 44 vol.% using the new electrolyte composition. 相似文献
11.
Micrometer and nanometer Al particles were codeposited with nickel by electrodeposition from a nickel sulfate bath containng a similar content of Al particles. The effect of Al particles size on the microstructure of the electrodeposited Ni-Al composite coatings was analyzed. The results indicated that at a given Al particles content the incorporation of Al nanoparticles instead of the microscale countparts significantly increased the particle number per unit volume in the composite, led to a more homogeneous distribution of particles, and finer Ni grains due to nucleation of smaller Ni grains on the surface of Al nanoparticles, which changed the direction of the local Ni growth and caused the formation of a fine equiaxed grain structure. 相似文献
12.
J. Luschitz 《Thin solid films》2009,517(7):2125-2131
The performance of CdTe solar cells as prototype of thin film solar cells strongly depends on film morphology. The needs for high solar cell performance using thin film materials will be addressed covering nucleation and growth control of thin film materials. In order to understand the basic growth mechanisms and their impact on cell performance, we have systematically investigated the growth of CdTe thin films by Close Spaced Sublimation (CSS) using the integrated ultra-high vacuum system DAISY-SOL. CdTe thin films were deposited on TCO/CdS substrates (transparent conductive oxide) held at 270 °C to 560 °C. The properties of the films were determined before and after CdCl2 treatment using X-ray diffraction and electron microscopy. In addition, solar cells were prepared to find correlations between material properties and cell efficiency. At low sample temperature the films tend to form compact layers with preferred (111) orientation which is lost at elevated temperatures above 450 °C. For CdS layers without (0001) texture there is in addition a low temperature regime (350 °C) with (111) texture loss. After activation treatment the (111) texture is lost for all deposited layers leading to strong recrystallisation of the grains. But the texture still depends on the previous growth history. The loss of (111) texture is evidently needed for higher performance. A clear correlation between cell efficiency and the texture of the CdTe film is observed. 相似文献
13.
G. Atthipalli R. EpurP.N. Kumta B.L. AllenY. Tang A. StarJ.L. Gray 《Thin solid films》2011,519(16):5371-5375
Growth of carbon nanotubes (CNTs) on bulk copper foil substrates has been achieved by sputtering a nickel thin film on Cu substrates followed by thermal chemical vapor deposition. The characteristics of the nanotubes are strongly dependent on the Ni film thickness and reaction temperature. Specifically, a correlation between the thin film nickel catalyst thickness and the CNT diameter was found. Two hydrocarbon sources investigated were methane and acetylene to determine the best conditions for growth of CNTs on copper. These results demonstrate the effectiveness of this simple method of directly integrating CNTs with highly conductive substrates for use in applications where a conductive CNT network is desirable. 相似文献
14.
15.
The visible light bactericidal ability of nitrogen doped TiO2 (TiON) film on Si (100) has been enhanced greatly (by 22%) through a single-mode microwave irradiation annealing (f = 2.45 GHz, 20 s) in comparison with the conventional heat treatment at the same temperature (500 °C, 300 s). Analyses of X-ray photoelectron spectroscopy and transmission electron microscopy showed that the microwave annealed TiON film had a higher nitrogen concentration and much better crystallinity, both of which contribute to its prior bactericidal ability under visible light. The optimized annealing parameters of microwave irradiation are 500 °C within 20 s. Increase of annealing temperature and irradiation time resulted in the decrease of nitrogen concentration within the film. The crystallized TiON film has an anatase but not a rutile structure at the annealing temperature up to 800 °C. 相似文献
16.
Woon Shin Law 《Thin solid films》2009,517(18):5425-9828
The effect of TiO2 film thickness and agglomerate size on the non-UV activated superhydrophilic wetting and antifogging characteristics of TiO2 films was investigated. Evidence from Atomic Force Microscopy analysis showed that surface roughness is the key parameter requiring control so as to retain the superhydrophilic wetting and antifogging behaviour of the synthesised films. Surface roughness can be tuned by simple manipulation of the multilayer assembly of TiO2 nanoparticles through varying the film thickness and agglomerate size. A film thickness of ~ 140 nm yielded the optimum roughness (root mean square = 23 nm) to give the best superhydrophilic wetting behaviour. Thicker films reduced the film roughness and were detrimental to their superhydrophilic wetting properties. Smaller agglomerate size was also found to be important in retaining film roughness. 相似文献
17.
The morphology and texture of Ge films grown under oblique angle vapor deposition on native oxide covered Si(001) substrates at temperatures ranging from 230 °C to 400 °C were studied using scanning electron microscopy, X-ray diffraction and X-ray pole figure techniques. A transition from polycrystalline to {001}<110> biaxial texture was observed within this temperature range. The Ge films grown at substrate temperatures < 375 °C were polycrystalline. At substrate temperatures of 375 °C and 400 °C, a mixture of polycrystalline and biaxial texture was observed. The 230 °C sample consisted of isolated nanorods, while all other films were continuous. The observed biaxial texture is proposed to be a result of the loss of the interface oxide layer, resulting in epitaxial deposition of Ge on the Si and a texture following that of the Si(001) substrates used. The rate of oxide loss was found to increase under oblique angle vapor deposition. 相似文献
18.
The structural and morphological transformations of TiO2 nanotube arrays (TNAs) treated by excimer laser annealing (ELA) were investigated as a function of the laser fluence using parallel and tilted modes. Results showed that the crystallinity of the ELA-treated TNAs reached only about 50% relative to that of TNAs treated by furnace anneal at 400 °C for 1 h. The phase transformation starts from the top surface of the TNAs with surface damage resulting from short penetration depth and limited one-dimensional heat transport from the surface to the bottom under extremely short pulse duration (25 ns) of the excimer laser. When a tilted mode was used, the crystallinity of TNAs treated by ELA at 85° was increased to 90% relative to that by the furnace anneal. This can be attributed to the increased area of the laser energy interaction zone and better heat conduction to both ends of the TNAs. 相似文献
19.
Hebatpuria VM Arafat HA Rho HS Bishop PL Pinto NG Buchanan RC 《Journal of hazardous materials》1999,70(3):1591-138
In this research, we investigated the use of an inexpensive thermally regenerated activated carbon as a pre-adsorbent in the solidification/stabilization of phenol-contaminated sand. Our results show that even the addition of very low amounts of regenerated activated carbon (1%–2% w/w sand) resulted in the rapid adsorption of phenol in the Chemical solidification/stabilization (S/S) matrix, with phenol leaching reduced by as much as 600%. Adsorption studies indicated that the adsorption of phenol on the reactivated carbon was found to be partially irreversible over time in the S/S waste form, indicating possible chemical adsorption. Pore-fluid analyses of the cement paste containing phenol suggested the formation of a calcium–phenol complex, which further reduced the amount of free phenol present in the pores. Studies using several micro-structural techniques, including field emission scanning electron microscopy, X-ray diffraction, fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy, indicated significant morphological changes in the cement matrix upon the addition of phenol and reactivated carbon. The hydration of cement in the presence of phenol was retarded concomitant with formation of amorphous portlandite. 相似文献
20.
The texture control of transparent oxide thin film, the crystalline orientation, is very important, because it is related to the electrical resistivity and the optical transparency. It is known that the crystal orientation could be controlled by varying precursor source, gas flow rate, and deposition temperature. We deposited fluorine-doped tin oxide (FTO) thin film on aluminoborosilicate glass by spraying water-based solution and ethyl alcohol-added solution. We showed in this research that (200) and (301) preferential orientation of FTO thin film can be controlled by the addition of ethyl alcohol to FTO coating solution. (200) oriented FTO thin film deposited from ethyl alcohol-added solution comprises of pyramidal crystallites with {111} polar faces, which contain {101} contact twin planes. {101} contact twin planes forms salient reentrant angle which provides nucleating sites and makes crystallites grow abnormally. (301) orientation is thought through Periodic Bond Chains of tin hydroxide which forms prismatic long crystallites. Prismatic crystallites are comprised of {110} crystal faces which contain {101} repeated contact twin. It is very helpful to control (200) or (301) oriented crystal formation in transparent conducting oxide film, because the texture affects the electrical and optical properties of transparent conducting oxide film. We suggest that ethyl alcohol addition plays a role to form crystallites with {111} polar faces corresponding to (200) preferential orientation. The crystal morphologies are changed by doping elements, precursor sources, deposition conditions like flow rate and temperatures, and solvents. 相似文献