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1.
A TiO 2 photocatalytic film was prepared by the sol–gel and dip-coating methods. Au-loaded TiO 2 photocatalytic films were produced by the photodeposition method. The photocatalytic activity of the films under UV irradiation
was evaluated by measuring the degradation of absorbance for a methylene blue (MB) aqueous solution. Au particles deposited
on the TiO 2 film improved the photocatalytic activity under the O 2 bubbling condition. On the other hand, under N 2 or Ar bubbling, the doubly reduced form of MB, leuco-methylene blue (LMB), was formed at the beginning of UV irradiation, and then both MB and LMB were decomposed gradually by
the photocatalytic reaction. In this process, Au particles on the TiO 2 film behave as electron traps. 相似文献
2.
Carbon xerogels synthesized from polycondensation of resorcinol with formaldehyde, having specific surface areas in the range 650 to 990 m 2 g −1 and variable degrees of surface oxidation, are used to prepare TiO 2-carbon xerogel composites by sol-gel methods. These composite materials are used to support Pt nanoparticles (5 wt.%) by the photodeposition technique. After a high temperature reduction treatment at 773 K, the obtained materials were characterized in order to assess the interactions between the phases Pt, TiO 2 and carbon xerogel. It is observed that the carbon xerogel acts as an adhesive agent of the TiO 2 and Pt particles, enhancing the interaction between the metal and the composite support. 相似文献
3.
Polyaniline (PANI) as a promising conducting polymer has been used to prepare polyaniline/TiO 2 (PANI/TiO 2) nanocomposite with core-shell structure as photocatalyst. Titanium dioxide (TiO 2) nanoparticles with an average crystal size of 21?nm were encapsulated by PANI via the in situ polymerization of aniline on the surface of TiO 2 nanoparticles. FT?CIR, UV-Vis-NIR, XRD, SEM and TEM techniques were used to characterize the PANI/TiO 2 core-shell nanocomposite. Photocatalytic activity of PANI/TiO 2 nanocomposite was investigated under both UV and visible light irradiations and compared with unmodified TiO 2 nanoparticles. Results indicated deposition of PANI on the surface of TiO 2 nanoparticles which improved the photocatalytic activity of pristine TiO 2 nanoparticles. 相似文献
4.
TiO 2 nanoparticles have been synthesized by solvent-free hydrothermal process. TiO 2 nanoparticles were annealed at 500°C for enhancing the characterization and the photocatalytic activity. The synthesized TiO 2 was characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), BET, and diffuse reflectance spectroscopy (UV-DR) techniques to study the morphology and structural configuration. The effects of different parameters such as the initial dye concentration, catalyst concentration, pH of the solution, light intensity, and reactive oxygen species (ROS) on relative photonic efficiencies and photocatalytic degradation kinetics of GRL were investigated, and the degradation of GRL follows pseudo-first order kinetics according to the Langmuir–Hinshelwood model. The ROS studies indicate that hydroxyl radicals and holes are the predominant reactive species within the same step, contributing up to 92.64%, hydroxyl radicals participate for about 55%, and holes share for about 37.64% in the photocatalytic degradation of GRL. 相似文献
5.
Titanium dioxide (TiO 2) absorbs only a small fraction of incoming sunlight in the visible region thus limiting its photocatalytic efficiency and concomitant photocatalytic ability. The large-scale application of TiO 2 nanoparticles has been limited due to the need of using an ultraviolet excitation source to achieve high photocatalytic activity. The inclusion of foreign chemical elements in the TiO 2 lattice can tune its band gap resulting in an absorption edge red-shifted to lower energies enhancing the photocatalytic performance in the visible region of the electromagnetic spectrum. In this research work, TiO 2 nanoparticles were doped with iron powder in a planetary ball-milling system using stainless steel balls. The correlation between milling rotation speeds with structural and morphologic characteristics, optical and magnetic properties, and photocatalytic abilities of bare and Fe-doped TiO 2 powders was studied and discussed. 相似文献
6.
TiO 2 was coated on nonporous transparent silica particles of 3.2 μm diameter by deposition of sol-gel-derived TiO 2 nanoparticles. Effects of water concentration, feed rate of titanium tetraisopropoxide (TTIP) solution and amount of supplied TTIP solution on the amount of TiO 2 coated on the silica particles were examined. Scanning electron microscopy observation confirmed that TiO 2 was coated on the silica particles in the form of ‘nanoparticles’ by using this method. Because of that, even though the TiO 2 surface area decreased due to sintering after calcination at high temperature to change the crystalline phase of TiO 2 to the anatase phase, the final surface area was still much larger than that of the original silica particles. The results also showed that as the water concentration increased, the amount of coated TiO 2 decreased. On the other hand, when the amount of supplied TTIP solution increased, the amount of coated TiO 2 increased. It was also confirmed that the feed rate of TTIP solution had little effect on the amount of coated TiO 2. The photocatalytic activities of the resulting TiO 2-coated silica particles were also evaluated by the photocatalytic decomposition of 2,4-dinitrophenol as a model substance. The results showed that the photocatalytic activity of the particles is not a function of the total surface area, but of the surface area in which anatase phase TiO 2 is exposed to the reaction space. The sedimentation velocity of the TiO 2-coated silica particles becomes about 5 orders of magnitude faster than that of the primary particles of the TiO 2. This indicates that the handling of the TiO 2 was also improved considerably by coating on the silica particles. 相似文献
7.
While nanostructured materials are of particular academic and practical interest, their recoverability and recyclability have been of paramount industrial and environmental concerns. In the present contribution, co-precipitation was demonstrated as a facile and cost-effective approach to incorporate magnetic sensitivity and enhance the recoverability of nanofibrous materials which were frequently utilized in catalysis, energy and medical applications, etc. In particular, reusable magnetic and photocatalytic hybrid nanofibers were generated by electrospinning and co-precipitation method. First, TiO 2 nanofibers were prepared through sol-gel reaction and electrospinning process. To improve their recoverability, CoFe 2O 4 nanoparticles were decorated onto the nanofibers' surfaces via co-precipitation of cobalt and iron ions in the presence of the nanofibers suspension. Furthermore, the resulting CoFe 2O 4-decorated TiO 2 nanofibers maintained their photocatalytic activity after the modification. When suspended in a solution or spread on a dried surfaces, these nanofibers could be recollected with a magnet. These findings suggested that incorporation of ferromagnetic into the nanofibers maintained their photocatalytic performance and reduced production cost as well as the risk of human and environmental exposure through solution and air. 相似文献
8.
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
9.
Superior antimicrobial activity of 2 wt.% Pt-dispersed TiO 2 thin film was observed in photokilling Gram-negative Escherichia coli bacteria within 5 min irradiation (640 μW cm −2, λ > 340 nm) from UV torch than bare TiO 2 film. Severe disruption of cell membrane has occurred over illuminated Pt-TiO 2 catalysts films coated with 100–300 μg powders per 5 cm 2 areas over sterilized glass slides. The Pt dispersion onto TiO 2 by impregnation–hydrogen reduction always exhibited better photokilling effect than Pt photodeposition, irrespective of Pt–TiO 2 dose and light exposure time. Similar trend in photoactivity difference between two Pt–TiO 2 catalysts is also observed in aqueous slurry because of the unlike surface structure of TiO 2 due to different annealing temperatures, size and nature of Pt particles dispersion onto TiO 2 photocatalysts. 相似文献
10.
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
11.
In this work, Pt nanoparticles were deposited onto the surface of Magnéli phase titanium suboxide (TiO x) nanoparticles using a microwave-assisted deposition method. The effect of different concentrations of Pt nanoparticles was investigated to evaluate the strong metal-support interactions (SMSIs) between Pt and TiO x based on their performance for the degradation of organic pollutant molecules. The adsorption and catalytic performance of the as-synthesized Pt/TiO x nanoparticles were evaluated with respect to the degradation of rhodamine B (RhB) molecules without any external energy source. The Pt/TiO x nanoparticles with Pt loading at 10 wt% (10%Pt/TiO x) exhibited a remarkable performance. The XPS, CV, and FTIR analyses confirmed the presence of RhB degradation reactions under dark condition. This remarkable performance of the Pt/TiO x nanoparticles was attributed to the SMSIs between Pt and Ti 3+ atoms, which improves their performance compared with Pt/TiO 2 nanoparticles, and high density of active sites due to their nanometer size, which results in better performance compared with that of Pt/TiO x submicron particles. 相似文献
12.
Highly ordered titanium dioxide–tungsten trioxide nanotubular composites (TiO 2–WO 3) were fabricated on titanium sheets by electrochemical anodizing. Platinum nanoparticles have been successfully deposited onto TiO 2–WO 3 nanotubes by UV light photoreduction method. In this work, X-ray diffraction, field emission scanning electron microscope, ultraviolet–visible spectroscopy and energy dispersive X-ray spectrometer methods were adopted to characterize the samples. The degradation of methylene blue (MB) was used as a model reaction to evaluate the photocatalytic activity of the obtained samples. After irradiated under visible light for 60 min, the degradation rate of MB solution on unmodified TiO 2–WO 3 and Pt/TiO 2–WO 3 reached 77 and 93 %, respectively. Under the same condition, no obvious photodegradation of MB was found for bare TiO 2 (T). Kinetic research showed that photodegradation process followed the first-order reaction; the apparent reaction rate constant of Pt/TiO 2–WO 3-1 was 4.56 × 10 ?2 min ?1 which is approximately 1.75 times higher than that on the unmodified TiO 2–WO 3. This work provides an insight into designing and synthesizing new TiO 2–WO 3 nanotubes based hybrid materials for effective visible light-activated photocatalysis. 相似文献
13.
A series of polypyrrole (PPy)/titanium dioxide (TiO 2) nanocomposites were prepared in different polymerization conditions by ‘in situ’ chemical oxidative polymerization. The
nanocomposites were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), X-ray
photoelectron spectroscopy spectra (XPS), and UV–Vis diffuse reflectance spectra. The photocatalytic degradation of methyl
orange (MO) was chosen as a model reaction to evaluate the photocatalytic activities of TiO 2/PPy catalysts. The results show that a strong interaction exists at the interface between TiO 2 and PPy, the deposition of PPy on TiO 2 nanoparticles can alleviate their agglomeration, PPy/TiO 2 nanocomposites show stronger absorbance than neat TiO 2 under the whole range of visible light. The obtained PPy/TiO 2 nanocomposites exhibit significantly higher photocatalytic activity than the neat TiO 2 on the degradation of MO aqueous solution under visible and UV light illumination. The reasons for improving the photocatalytic
activity were also discussed. 相似文献
14.
Pd-Pt/graphene-TiO 2 nanocomposites were synthesized via a facile ultrasonic and hydrothermal method. For the functionalization of graphene, large area graphene obtained by chemical vapor deposition method was oxidized by 3-chloroperoxybenzoic acid. The functionalized graphene oxide was decorated with TiO 2. And then, Pt and Pd nanoparticles were dispersed on graphene surface, simultaneously. The characterizations of “as-prepared” samples were studied by X-ray diffraction (XRD), transmission electron microscope (TEM), Raman, specific surface area (BET) and with energy dispersive X-ray (EDX). The photocatalytic activity of the Pd-Pt/graphene-TiO 2 nanocomposite catalyst was evaluated by H 2 evolution under UV light. Pd-Pt/graphene-TiO 2 (Pd-Pt/G-TiO 2) exhibited higher photocatalytic activities than control experimental group samples (TiO 2, G-TiO 2, Pd/G-TiO 2 and Pt/G-TiO 2) under UV light irradiation. 相似文献
15.
TiO 2/Pt/TiO 2 (TPT) multilayered films with different thicknesses of Pt layers from about 0.75 to 12 nm were prepared by radio frequency magnetron sputtering method. The as-prepared films were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, UV-visible diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The photocatalytic activity of the samples was evaluated by the photocatalytic decolorization of methyl blue aqueous solution under ultraviolet light irradiation. The photocatalytic activities of all TPT multilayer films were higher than that of the pure TiO 2 films. When Pt thickness was increased to 3 nm, the measured photocatalytic activity of the TPT film was highest, and exceeded that of the pure TiO 2 films by a factor of more than three times. Such enhancement was ascribed to the presence of Pt layer, which inhibits the recombination of the photogenerated charge and carriers, as well as modifies the crystallinity of the TiO 2 top layer. 相似文献
16.
In this work, heterostructures were obtained by uniformly assembling NiO nanoparticles on the surface-coarsened TiO 2 nanobelts through a precipitation process. The uniform assembling of NiO nanoparticles led to a large number of nano-p-n-junction heterostructures on the surface of the TiO 2 nanobelts, where NiO and TiO 2 are p- and n-type semiconductors, respectively. Compared with both pure NiO nanoparticles and TiO 2 nanobelts, NiO nanoparticles/TiO 2 surface-coarsened nanobelt heterostructured composite exhibited a greatly enhanced photocatalytic activity in the decomposition of a model dye compound methyl orange under ultraviolet light irradiation. It was argued that the nano-p-n-junctions effectively reduce the recombination of electrons and holes, thus resulting in enhanced photocatalytic property of the heterostructured composites. The better performance of the surface-coarsened nanobelts is due to the increased photo absorption and production of charge carriers, which renders the composites with further enhanced photocatalytic performance. The established approach allows the control of the nano-p-n junction heterostructure on the nanobelts, and hence, their photocatalytic effect. 相似文献
17.
TiO 2 nanotubes were fabricated by a hydrothermal method. Silver nanoparticles with diameters around 3–5 nm were loaded onto the
surface of TiO 2 nanotubes via a deposition approach followed by a photochemical reduction process under ultraviolet irradiation. Transmission
electron microscopy (TEM), N 2 adsorption measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-vis diffuse
reflectance spectroscopy (UV-vis), and fluorescence spectroscopy (FL) were applied to characterize the as-prepared Ag/TiO 2 nanotube composites. The photocatalytic activity of the as-prepared materials was investigated by photodegrading of methyl
orange. The results showed that silver particles were in zero oxidation state and highly dispersed on the surface of TiO 2 nanotubes when the concentration of Ag + was low. The presence of metallic silver can help the electron-hole separation by attracting photoelectrons. The Ag/TiO 2 nanotube composites with a suitable amount of silver showed a further improvement on the photocatalytic activity for degradation
of methyl orange in water. 相似文献
18.
Photocatalytic wastewater treatment is expected to become a sustainable way of eliminating toxic chemicals. Due to the surface-driven mechanism of the photocatalysis, surface area of the catalyst material plays a crucial role in the efficiency of the process, which is usually achieved by nanoparticles. However, using powder materials introduces a new problem: removing the catalyst materials out of clean water. As an alternative, atomic layer deposition (ALD) can form conformal thin films on high surface area substrates providing an immobilization route with high photocatalytic activity. Textile materials are inexpensive and accessible therefore good candidates for the substrate materials. Here, we deposit thin films on TiO2 on fiberglass fabrics and investigate the photocatalytic activity. Since the as-deposited ALD TiO2 films are amorphous, they have very limited photocatalytic activity. Upon thermal treatment of the films after deposition, photocatalytic activity is achieved. After four hours of exposure to the solar simulator and UV lamp, TiO2-coated fibers demonstrated much higher photocatalytic activity than films on planar substrates previously described in the literature. The photocatalytic activity and structure of the coated fibers were investigated using XRD, XPS, UV–Vis, and PL analyses. 相似文献
19.
Herein, we report the ultrasonic-assisted precipitation technique for the fabrication of Cu-doped TiO 2 nanoparticles. The prepared sample showed high crystallinity, purity and nanoparticles like structure with the diameter in the range of 10–22 nm. The bandgap for Cu-doped TiO 2 nanoparticles was estimated to be 2.91 eV using Tauc plot, which is considerable for improving the light-harvesting capacity. Further, the prepared Cu-doped TiO 2 was used as photocatalyst for the eradication of ofloxacin (OFX), an antibiotic from an aqueous phase under visible illuminations. About 72% degradation of OFX (10 mg/L, pH 7) was achieved with Cu-doped TiO 2 nanoparticles after 180 min of visible illumination. The probable photocatalytic mechanism for the decomposition of OFX has been proposed based on reactive species trapping study. Moreover, the antibiotic efficiency of OFX was investigated against Escherichia coli and it was observed that its antimicrobial activity was significantly diminished after the photocatalytic decomposition of the OFX solution with synthesized nanoparticles. 相似文献
20.
TiO 2–SiO 2 metal oxide materials with a mesostructure have been prepared by a novel method in which hydrolysis and condensation of titanium tetraisopropoxide (TTIP) and tetraethoxysilane (TEOS) were controlled by the pH change of acidic solution. The Pt-modified TiO 2–SiO 2 catalysts were synthesized by the photo-reduction method. The resulting materials showed a high photocatalytic activity for the photodegradation of methyl orange in the visible-light range. A reaction mechanism was proposed and discussed. 相似文献
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