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1.
Anna Nasonova Dong-Joo Kim Woo-Sik Kim Kyo-Seon Kim 《Research on Chemical Intermediates》2008,34(4):309-318
We analyzed the dielectric pellet bed discharge-photocatalyst hybrid process for NO and SO2 removal. A cylindrical-wire type discharge reactor was packed with glass beads as dielectric pellets and the plasmas were
generated by dielectric pellet bed discharge. The TiO2 photocatalysts were coated onto the glass beads by the dip-coating method and were activated by the light from discharge.
Experiments were carried out for three cases: NO removal only, SO2 removal only, and simultaneous NO and SO2 removal. As the voltage applied to the plasma reactor increased, or as the residence time increased, the NO and SO2 removal efficiencies increased. With increasing initial NO and SO2 concentrations, the NO and SO2 removal efficiencies decrease. The removal efficiencies for simultaneous NO and SO2 removal are lower than those for NO only or SO2 only. 相似文献
2.
Lili Chen Mingrong Shen Liang Fang Yu Xu 《Journal of Sol-Gel Science and Technology》2007,42(3):299-303
A TiO2 thin buffer layer was introduced between the (Pb0.4Sr0.6)TiO3 (PST) film and the Pt/Ti/SiO2/Si substrate in an attempt to improve their electrical properties. Both TiO2 and PST layers were prepared by a chemical solution deposition method. It was found that the TiO2 buffer layer increased the (100)/(001) preferred orientation of PST and decreased the surface roughness of the films, leading
to an enhancement in electrical properties including an increase in dielectric constant and in its tunability by DC voltage,
as well as a decrease in dielectric loss and leakage current density. At an optimized thickness of the TiO2 buffer layer deposited using 0.02 mol/l TiO2 sol, the 330-nm-thick PST films had a dielectric constant, loss and tunability of 1126, 0.044 and 60.7% at 10 kHz, respectively,
while the leakage current density was 1.95 × 10−6 A/cm2 at 100 kV/cm. 相似文献
3.
At present, carbon dioxide is considered the largest contributor among greenhouse gases. This review covers the current state
of problem of carbon dioxide emissions from industrial and combustion processes, the principle of photocatalysis, existing
literature related to photocatalytic CO2 reduction over TiO2 based catalysts and the effects of important parameters on the process performance including light wavelength and intensity,
type of reductant, metal-modified surface, temperature and pressure.
Presented at the 34th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 21–25 May
2007. 相似文献
4.
Stefano Livraghi Maria Cristina Paganini Mario Chiesa Elio Giamello 《Research on Chemical Intermediates》2007,33(8):739-747
Nitrogen-doped TiO2, a novel photocatalyst active in the decomposition of organic pollutants using visible light, contains several different
types of paramagnetic centers. These are molecular species, such as NO and NO2 radicals and other species, deeply interacting with the TiO2 structure. All or part of these species is related to specific properties of the solid. Electron paramagnetic resonance has
been employed to characterize the N-containing paramagnetic species present in N-doped anatase TiO2 powders obtained via sol-gel synthesis. In the present work attention is focused on molecular species generated during the synthesis process and
segregated in cavities of the TiO2 structure. 相似文献
5.
Li Chen Haixia Shen Zhen Lu Cang Feng Su Chen Yanru Wang 《Colloid and polymer science》2007,285(13):1515-1520
TiO2–SiO2 composite nanoparticles were prepared by a sol–gel process. To obtain the assembly of TiO2–SiO2 composite nanoparticles, different molar ratios of Ti/Si were investigated. Polyurethane (PU)/(TiO2–SiO2) hybrid films were synthesized using the “grafting from” technique by incorporation of modified TiO2–SiO2 composite nanoparticles building blocks into PU matrix. Firstly, 3-aminopropyltriethysilane was employed to encapsulate TiO2–SiO2 composite nanoparticles’ surface. Secondly, the PU shell was tethered to the TiO2–SiO2 core surface via surface functionalized reaction. The particle size of TiO2–SiO2 composite sol was performed on dynamic light scattering, and the microstructure was characterized by X-ray diffraction and
Fourier transform infrared. Thermogravimetric analysis and transmission electron microscopy (TEM) employed to study the hybrid
films. The average particle size of the TiO2–SiO2 composite particles is about 38 nm when the molar ratio of Ti/Si reaches to1:1. The TEM image indicates that TiO2–SiO2 composite nanoparticles are well dispersed in the PU matrix. 相似文献
6.
Nanodisperse TiO2 hydrosol and two of its fractions stabilized by HCl are studied. The anatase nanocrystalline fractions are obtained by the stepped coagulation of the stable sol using dependence of coagulation thresholds on size of nanocrystallites. X-Ray investigation in small and wide angles of scattering has revealed that the anatase nanocrystallites have a shape of 2.5–3 nm thick elongated plates with 8–18 nm lateral sizes. The concentrated hydrosols with the reduced HCl content prepared from the anatase fractions are shown to form an ordered structure. Narrow fractions of TiO2 nanocrystallites obtained from the stable hydrosols seem to be promising for the preparation of highly ordered structures with a nanometer periodicity. 相似文献
7.
Yu. I. Gnatyuk V. I. Yatskiv N. P. Smirnova V. M. Granchak A. M. Eremenko 《Theoretical and Experimental Chemistry》2005,41(6):371-376
We have used the sol-gel template synthesis method to obtain mesoporous zirconium-containing titanium dioxide films and have
studied their structural and sorption characteristics, surface acid function, and photocatalytic activity during gas-phase
oxidation of aliphatic alcohols. We have shown that the zirconium content changes the acidity and specific surface area of
the films, determining the rate at which the studied processes occur and the relative yield of reaction products.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 41, No. 6, pp. 354–359, November–December, 2005. 相似文献
8.
Influences of α-MnO2, β-MnO2, and δ-MnO2 on the photocatalytic activity of Degussa P-25 TiO2 have been investigated through the photocatalytic degradation of methyl orange. The TiO2 photocatalyst, before and after being contaminated by MnO2, was characterized by UV-visible diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL), and X-ray photoelectron
spectroscopy (XPS). The results showed that photocatalytic activity of TiO2 could be inhibited significantly or completely deactivated due to the presence of even a small amount of MnO2 particles. It was found that the poisoning effect varied with the crystal phases of MnO2 and the effect was in the order δ-MnO2 >α-MnO2 >β-MnO2. The poisoning effect was attributed to the formation of heterojunctions between MnO2 and TiO2 particles. The heterojunctions changed the chemical state of Ti4+ and O2− sites in the crystalline phase of TiO2. MnO2 in contact with TiO2 particles also broadens the band-gap of TiO2, which decreases UV absorption of TiO2. It can also create some deep impurity energy levels serving as photoelectron-photohole recombination center, which accelerates
the electron-hole recombination.
Supported by the National Natural Science Foundation of China (Grant No. 20477009) and the Natural Science Foundation of Hebei
Province (Grant No. E2005000183) 相似文献
9.
M. Crişan Ana Brăileanu M. Răileanu D. Crişan V. S. Teodorescu R. Bîrjega V. E. Marinescu J. Madarász G. Pokol 《Journal of Thermal Analysis and Calorimetry》2007,88(1):171-176
Pure TiO2
and S-doped TiO2 sol–gel nanopowders were prepared
by controlled hydrolysis-condensation of titanium alkoxides. The influence
of different Ti-alkoxides (tetraethyl-, tetraisopropyl- and tetrabutyl-orthotitanate)
used in obtaining TiO2 porous materials in similar
conditions (water/alkoxide ratio, solvent/alkoxide ratio, pH and temperature
of reaction) has been investigated. The relationship between the synthesis
conditions and the properties of titania nanosized powders, such as thermal
stability, phase composition, crystallinity, morphology and size of particles,
BET surface area and the influence of dopant was investigated. The nature
of the alkyl group strongly influences the main characteristics of the obtained
oxide powders, fact which is pointed out by thermal analysis, X-ray diffraction,
TEM and BET surface area measurements. 相似文献
10.
A. G. Bubnov E. Yu. Burova V. I. Grinevich V. V. Rybkin J.-K. Kim H.-S. Choi 《Plasma Chemistry and Plasma Processing》2006,26(1):19-30
This study investigated the processes for the destruction of phenol and its derivatives (resorcin and pyrocatechol) in aqueous
solutions under the action of an oxygen dielectric barrier discharge (DBD) at atmospheric pressure in the presence or absence
of catalysts in the plasma zone. It was shown that the DBD had a high decomposition efficiency for phenol and its derivatives
(up to 99%). Phenol was the most stable and pyrocatechol was the least. In a plasma-catalytic hybrid process, the effective
rate constants for phenol, resorcin and pyrocatechol decomposition were 11, 4 and 2.5 times higher, respectively, than those
for the DBD treatment without catalysts. The process also resulted in a 1.4, 1.6 and 1.2 times higher rate of carboxylic acid
formation for phenol, resorcin and pyrocatechol, respectively. The fractional conversion into the respective carboxylic acids
reached 56% for phenol and 68% for resorcin and pyrocatechol. 相似文献
11.
Yanhuai Ding Ping Zhang Zhilin Long Yong Jiang Fu Xu Jianguang Lei 《Journal of Sol-Gel Science and Technology》2008,46(2):176-179
TiO2 nanofibers were prepared from tetrabutyl titanate sol precursors by using electrospun method. X-ray diffraction (XRD) and
atomic force microscope (AFM) were used to characterize their crystal structure and morphology feature. The results demonstrated
that TiO2 nanofibers possessed anatase phase and the average diameter of TiO2 nanofibers was about 150 nm. The photocatalytic property of TiO2 nanofibers was evaluated for the photodecomposition of methyl orange solution. And TiO2 nanofibers exhibited high photocatalytic activities with transfer efficiency about 100% after 20 min. 相似文献
12.
Within the framework of the density functional theory (DFT), the electronic structure of monooxodioxovanadium functional groups in tetrahedral coordination, which model the active centers (ACs) of fine supported catalysts V2O5/SiO2 and V2O5/TiO2, has been analyzed. The optimal structures of three ACs as possible models of monomeric and polymeric oxovanadium forms on the carriers with low vanadium content were determined. The modified DFT method involving the time dependence of Kohn-Sham equation (TDDFT) was used for the adopted AC models to calculate the energies of the excited states, and optical spectra of the absorption in 25000–60000 cm?1 region were reconstructed on their base. The spectrum in this region is due to O → V charge transfer. The features of electronic spectra with the charge transfer for V2O5/SiO2 and V2O5/TiO2 catalysts and the vibrational spectra of three AC models corresponding to the monomeric and dimeric oxovanadium forms of the supported catalysts V2O5/SiO2 and V2O5/TiO2 were defined. The detailed interpretation of normal vibration frequencies is given. The frequencies typical of the monomeric and dimeric oxovanadium forms on the carrier surface were identified. 相似文献
13.
Jianxia Jiao Qun Xu Limin Li Takano Tsubasa Takaomi Kobayashi 《Colloid and polymer science》2008,286(13):1485-1491
Titania–silica composite have been prepared using polyethylene glycol (PEG) with different molecular weights (M
w), PEG20000, PEG10000, and PEG2000, as template in supercritical carbon dioxide (SC CO2). The composite precursors were dissolved in SC CO2 and impregnated into PEG templates using SC CO2 as swelling agent and carrier. After removing the template by calcination at suitable temperature, the titania–silica composite
were obtained. The composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and nitrogen
sorption–desorption experiment. Photocatalytic activity of the samples has been investigated by photodegradation of methyl
orange. Results indicate that there are many Si–O–Ti linkages in the TiO2/SiO2 composite; the PEG template has a significant influence on the structure of TiO2/SiO2. In addition, the TiO2/SiO2 prepared with PEG10000 exhibited high photocatalytic efficiency. So this work supplies a clue to control and obtain the TiO2/SiO2 composite with different photocatalytic reactivity with the aid of suitable PEG template in supercritical CO2. 相似文献
14.
To enhance film conformality together with electrical property suitable for dynamic random access memory (DRAM) capacitor
dielectric, the effects of oxidant and post heat treatment were investigated on aluminum and titanium oxide (Al2O3–TiO2) bilayer (ATO) thin film formed by atomic layer deposition method. For the conformal deposition of Al2O3 thin film, the O3 oxidant required a higher deposition temperature, more than 450 °C, while H2O or combined oxygen sources (H2O+O3) needed a wide range of deposition temperatures ranging from 250 to 450 °C. Conformal deposition of the TiO2 thin film was achieved at around 325 °C regardless of the oxidants. The charge storage capacitance, measured from the ATO
bilayer (4 nm Al2O3 and 2 nm TiO2) deposited at 450 °C for Al2O3 and 325 °C for TiO2 with O3 oxidant on the phosphine-doped poly silicon trench, showed about 15% higher value than that of 5 nm Al2O3 single layer thin film without any increase of leakage current. To maintain the improved electrical property of the ATO bilayer
for DRAM application, such as enhanced charge capacitance without increase of leakage current, upper electrode materials and
post heat treatments after electrode formation must be selected carefully.
Dedicated to Professor Su-Il Pyun on the occasion of his 65th birthday. 相似文献
15.
Junseo Choi Ji-Young Ban Suk-Jin Choung Jinsoo Kim Haznan Abimanyu Kye Sang Yoo 《Journal of Sol-Gel Science and Technology》2007,44(1):21-28
Mesoporous TiO2/γ-Al2O3 composite granules were prepared by combining sol–gel/oil-drop method, using various titania solution. The product granules
can be used as a photocatalyst or adsorbent in moving, fluidized bed reactors. The phase composition and pore structure of
the granules can be controlled by calcination temperature and using different titania solution. In the photocatalysis of NH3 decomposition, TiO2/γ-Al2O3 granules using Degussa P25 powder treated thermally at 450 °C showed the highest catalytic ability. However, TiO2/γ-Al2O3 granules using titania made by hydrothermal method had comparable performance in NH3 decomposition. 相似文献
16.
Preparation of nanocrystalline Fe-doped TiO<Subscript>2</Subscript> powders as a visible-light-responsive photocatalyst 总被引:1,自引:0,他引:1
Nanocrystalline Fe-doped TiO2 powders were prepared using TiOSO4, urea, and Fe(NO3)3 · 9H2O as precursors through a hydrothermal method. The as-synthesized yellowish-colored powders are composed of anatase TiO2, identified by X-ray diffraction (XRD). The grain size ranged from 9.7 to 12.1 nm, calculated by Scherrer’s method. The specific
surface area ranged from 141 to 170 m2/g, obtained by the Brunauer–Emmett–Teller (BET) method. The transmission electron microscopy (TEM) micrograph of the sample
shows that the diameter of the grains is uniformly distributed at about 10 nm, which is consistent with that calculated by
Scherrer’s method. Fe3+ and Fe2+ have been detected on the surface of TiO2 powders by X-ray photoelectron spectroscopy (XPS). The UV–Vis diffuse reflection spectra indicate that the light absorption
thresholds of the Fe-doped TiO2 powders have been red-shifted into the visible light region. The photocatalytic activity of the Fe-doped TiO2 was evaluated through the degradation of methylene blue (MB) under visible light irradiation. The Fe-doped TiO2 powders have shown good visible-light photocatalytic activities and the maximum degradation ratio is achieved within 4.5 h. 相似文献
17.
Shinichi Kawasaki Keiichi Maki Shuai Yuan Yasuyuki Matsumura Kohsuke Mori Hiromi Yamashita 《Research on Chemical Intermediates》2009,35(3):299-304
TiO2 photocatalysts were synthesized by a hydrothermal method from tetraisopropyl orthotitanate (TPOT) in the presence of NH4F with different NH4F/Ti molar ratios (0, 0.25, and 1). The formation of a well-crystallized anatase phase of TiO2 and the suppression of phase transition to rutile were observed, even at high calcination temperature, owing to the effects
of NH4F. The TiO2 synthesized hydrothermally with NH4F exhibited absorption with a shift to the longer wavelengths of the visible-light region. The hydrothermally synthesized
TiO2 with a moderate amount of NH4F exhibited high photocatalytic activity for the degradation of alcohol diluted in water under both UV-light and visible-light
irradiations. 相似文献
18.
Julian R. Osman Joe A. Crayston Allin Pratt David T. Richens 《Journal of Sol-Gel Science and Technology》2007,44(3):219-225
Mixed IrO2–TiO2 oxides were prepared by the sol–gel method upon acid-catalysed hydrolysis of an iridium solution in ethanol mixed with titanium
tetraethoxide in ethanol. The iridium solution was obtained by reaction of the sodium hexachloroiridate(IV) precursor in the
presence of sodium ethoxide in ethanol. Gels were formed in all but the high-Ir samples. Analysis of the dried gels showed
minority-phase enrichment at the surface and the presence of Ir(III), while microscopy showed evidence for dispersed iridium-containing
nanoparticles (1–20 nm in diameter). XRD powder patterns of the calcined material showed peaks due to a small amount of crystalline
NaCl impurity which could be removed by washing. This left amorphous phases, except in the Ir:Ti 3:2 case, which showed evidence
for the presence of separate crystalline oxide phases: anatase, IrO2 and Ti
x
Ir1−x
O2. 相似文献
19.
Hiroshi Taoda 《Research on Chemical Intermediates》2008,34(4):417-426
Recently, environmental disruption is proceeding on a global scale through the consumption of huge amounts of fossil fuels
and the emission of various chemical substances. However, these substances resist bio-treatment. TiO2 generates electrons and holes by irradiation with light. Most organic micro-pollutants, including dioxins, are decomposed
into carbon dioxide and water by the effect of the holes with high oxidative potential. By using such a photocatalytic reaction,
various applications are feasible for environmental cleanup. In general, TiO2 powder has been utilized as photocatalyst, although TiO2 powder photocatalyst has several disadvantages: (1) it is difficult to handle, (2) photocatalytic reaction is slow and it
takes a lot of time for treatment and (3) it is difficult to apply to plastics and textiles, because the photocatalyst decomposes
them. We have developed a photocatalyst suitable for practical use and have developed high-activity photocatalysts such as
TiO2 photocatalytic transparent film, photocatalytic silica-gel, apatite-coated TiO2 photocatalyst usable for plastics and textiles, photocatalytic paper, photocatalytic blue charcoal and photocatalytic oxygen
scavenger. The application of these high-activity photocatalysts has been studied in deodorization, anti-bacterial, self-cleaning,
anti-stain, water treatment, air purification such as photocatalytic decomposition of dioxins and VOC, and NO
x
removal. Now various photocatalytic articles using these new photocatalyst materials are on the market in Japan. Photocatalytic
technology can create many valuable products for environmental use all over the world. 相似文献
20.
The semiconductor properties of the interface TiO2/electrolyte in high organized porous oxide structures were analyzed by means of impedance spectroscopy near the flat band
potential. The impedance and capacitance studies performed on the as-anodized and thermally treated samples (anatase) indicate
the presence of a duplex structure formed by (1) the oxide at the bottom of the pores and (2) the walls of pores with different
donor densities and surface state concentrations. 相似文献