共查询到20条相似文献,搜索用时 31 毫秒
1.
Uraiwan Sirimahachai Nicholas Ndiege Ramesh Chandrasekharan Sumpun Wongnawa Mark A. Shannon 《Journal of Sol-Gel Science and Technology》2010,56(1):53-60
Nanosized TiO2 and nano-anatase TiO2 decorated on SiO2 spherical core shells were synthesized by using a sol–gel method. The synthesized pure TiO2 nano particle and TiO2 grafted on SiO2 sphere with various ratios have been characterized for their structure and morphologies by X-ray diffraction (XRD), X-ray
photoelectron spectroscopy (XPS), Fourier transform infrared spectrophotometry (FTIR) and transmission electron microscopy
(TEM). Their surface areas were measured using the BET method. The photocatalytic activity of all nanocomposites was investigated
using methylene blue as a model pollutant. The synthesized TiO2/SiO2 particles appeared to be more efficient in the degradation of methylene blue pollutant, as compared to pure TiO2 particles. 相似文献
2.
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
3.
Yun Zhou Can Guo Shengqi Xi Chongfeng Sun Hongjing Wu Feihu Shang 《Research on Chemical Intermediates》2017,43(3):1495-1512
ZnFe2O4 nanoparticles sensitized by C-modified TiO2 hybrids (ZnFe2O4–TiO2/C) were successfully prepared by a feasible method. The ZnFe2O4 nanoparticles were prepared by mechanical alloying and annealing. The residual organic compounds in the synthetic process of TiO2 were selected as the carbon source. The as-prepared composites were characterized by X-ray diffraction, Raman spectroscopy, X-ray fluorescence, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible light diffuse reflectance spectroscopy (UV–Vis) and N2 adsorption–desorption analysis. The photocatalytic activity of the photocatalysts was measured by degradation of methyl orange under ultraviolet (UV) light and simulated solar irradiation, respectively. The results show that the carbon did not enter the TiO2 lattice but adhered to the surface of TiO2. The photocatalytic activity of the as-prepared C-modified TiO2 (TiO2/C) improved both under UV and simulated solar light irradiation, but the improvement was not dramatic. Introduction of ZnFe2O4 into the TiO2/C could enhance the absorption spectrum range. The ZnFe2O4–TiO2/C hybrids exhibited a higher photocatalytic activity both than that of the pure TiO2 and TiO2/C under either UV or simulated solar light irradiation. The complex synergistic effect plays an important role in improving the photocatalytic performance of ZnFe2O4–TiO2/C composites. The optimum photocatalytic performance was obtained from the ZnFe2O4(0.8 wt%)–TiO2/C sample. 相似文献
4.
SiO2/TiO2 hybrid nanofibers were prepared by electrospinning and applied for photocatalytic degradation of methylene blue (MB). The phase structure, specific surface area, and surface morphologies of the SiO2/TiO2 hybrid nanofibers were characterized through thermogravimetry (TG), X-ray diffraction (XRD) analysis, Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM), etc. XRD measurements indicated that doping of silica into TiO2 nanofibers can delay the phase transition from anatase to rutile and decrease the grain size. SEM and BET characterization proved that silica doping can remarkably enhance the porosity of the SiO2/TiO2 hybrid nanofibers. The MB adsorption capacity and photocatalytic activity of the SiO2/TiO2 hybrid nanofibers were distinguished experimentally. It was found that, although increased silica doping content could enhance the MB adsorption capacity, the intrinsic photocatalytic activity gradually dropped. The SiO2 (10 %)/TiO2 composite nanofibers exhibited the highest MB degradation rate, being superior to SiO2 (20 %)/TiO2 or pure TiO2. 相似文献
5.
Nanostructures TiO2–SiO2 photocatalysts were successfully synthesized using the sol-gel method, hydro-calcination, co-precipitation and room-temperature solid-phase synthesis technology. X-ray powder diffraction pattern (XRD), Fourier transform infrared spectrum (FTIR), photoluminescence (PL) spectra, thermal analyses (TG–DTA), scanning electron micrographs (SEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) were used to characterize the as-synthesized catalysts. Photocatalytic performances of the catalysts were evaluated by the degradation of methyl orange (MO) under s imulated natural light and the degradation rate of MO is 97.2%. The composites showed a good stability: after five recycling runs there are no significant decreases in the photocatalytic activity. The photodegradation of methylene blue, rhodamine B, methyl violet, naphthol green B, basic fuchsin, malachite green, and methyl red were also tested, and the degradation rate of dyes could reach over 94.2 %. A possible mechanism for the photocatalysis with the TiO2–SiO2 was proposed. 相似文献
6.
Selective catalytic reduction (SCR) with ammonia has been considered as the most promising technology, as its effect deals with the NOX. Novel Fe-doped V2O5/TiO2 catalysts were prepared by sol–gel and impregnation methods. The effects of iron content and reaction temperature on the catalyst SCR reaction activity were explored by a test device, the results of which revealed that catalysts could exhibit the best catalytic activity when the iron mass ratio was 0.05%. It further proved that the VTiFe (0.05%) catalyst performed the best in denitration and its NOX conversion reached 99.5% at 270 °C. The outcome of experimental procedures: Brunauer–Emmett–Teller surface area, X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction and adsorption (H2-TPR, NH3-TPD) techniques showed that the iron existed in the form of Fe3+ and Fe2+ and the superior catalytic performance was attributed to the highly dispersed active species, lots of surface acid sites and absorbed oxygen. The modified Fe-doped catalysts do not only have terrific SCR activities, but also a rather broad range of active temperature which also enhances the resistance to SO2 and H2O. 相似文献
7.
Chijia Wang Huaiyuan Wang Li Zhao Shuhui Yang Yanji Zhu 《Catalysis Surveys from Asia》2016,20(1):34-40
In this work, NiWO4 nanoparticles were prepared by a novel simple method and loading on the mesoporous TiO2 whiskers (TiO2(w)) carrier as the precursor of NiWS. In addition, the NiWS-TiO2(w) catalysts showing high hydrodesulfurization (HDS) activity is described. The structure and chemical composition of the as-prepared samples were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction, NH3-temperature programmed desorption and transmission electron microscopy, respectively. Results indicate that smaller crystallite size and better dispersion of active NiWO4 particles could be achieved by using TiO2(w) as the support to disperse NiWO4 nanoparticles. TiO2(w) can also decrease the reduction temperature of Ni–W metal oxide and promote a highly sulfidation degree of Ni and W active sites. The obtained NiWS-TiO2(w) catalysts show much higher dibenzothiop HDS activity than the unsupported NiWS catalyst, and the sulphur content of desulfurated oil can reach 20 ppm at the mild condition of 260 °C and 2 Mpa. 相似文献
8.
Trino Suárez Bernardo Fontal Joel E. Vielma Marisela Reyes Fernando Bellandi Pedro Cancines Juan C. Díaz Yuraima Fonseca 《Transition Metal Chemistry》2011,36(6):617-620
RuCl2(DMSO)2(NC5H4CO2Na-3)2 is very soluble in the ionic liquid (IL) 1-n-butyl-3-methylimidazolium tetrafluoroborate, [(BMIM)BF4]. The complex was prepared by reacting RuCl2(DMSO)4 with NC5H4CO2Na-3, sodium nicotinate, in toluene, and was characterized by spectroscopic methods. The complex catalyzes the hydrogenation
of 1-hexene (600 psi H2, 100 °C) in a two-phase system consisting of cyclohexane/[(BMIM)BF4] with 75% conversion in 24 h and modest substrate isomerization. The complex shows good stability and can be reused several
times with little loss in activity. 相似文献
9.
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
10.
Differential scanning calorimetry (DSC) and thermomechanical analysis (TMA) were used to study the thermal behaviour of (50-x)Na2O-xTiO2-50P2O5 and 45Na2O-yTiO2-(55-y)P2O5 glasses. The addition of TiO2 to the starting glasses (x=0 and y=5 mol% TiO2) resulted in a nonlinear increase of glass transition temperature and dilatation softening temperature, whereas the thermal
expansion coefficient decreased. All prepared glasses crystallize under heating within the temperature range of 300–610°C.
The contribution of the surface crystallization mechanism over the internal one increases with increasing TiO2 content. With increasing TiO2 content the temperature of maximum nucleation rate is also gradually shifted from a value close to the glass transition temperature
towards the crystallization temperature. X-ray diffraction measurements showed that the major compounds formed by glass crystallization
were NaPO3, TiP2O7 and NaTi2(PO4)3. The chemical durability of the glasses without titanium oxide is very poor, but with the replacement of Na2O or P2O5 by TiO2, it increases sharply. 相似文献
11.
Elham Safaei Sajjad Mohebbi Mehdi Irani 《Journal of Sol-Gel Science and Technology》2018,86(1):170-174
TiO2/WO3 nanocomposite with nanodisk morphology was prepared and successfully used as a photocatalyst. The nanocomposite was obtained via sonochemical and hydrothermal methods, using pomegranate juice as a capping agent. The products were characterized by FE-SEM imaging, BET, EDAX spectroscopy, X-ray diffraction, DRS, and FT-IR spectroscopy. TiO2/WO3 nanocomposite showed high sensitivity to absorb visible light in compared to TiO2. In an optimized condition, the yield of the aerobic photocatalytic oxidation of benzyl alcohol derivatives reached to 65% for the TiO2/WO3 nanocomposite, while the conversion percent of the derivatives was less than 8% and 50% on the TiO2 and WO3 nanoparticles, respectively. Experimental results were supported by density functional theory (DFT) calculations. The DFT results in several solvents of different dielectric constants, confirmed the strong dependence of light absorption and photocatalytic activity to adsorption energy of the substrates on the surface of the nanoparticles (Ead). In addition, the theoretical results showed an inverse correlation between the adsorption energy of benzyl alcohol and its conversion percent, accordance to the experimental trend. 相似文献
12.
Hiromasa Nishikiori Makoto Tagahara Leo Mukoyama Tsuneo Fujii 《Research on Chemical Intermediates》2010,36(8):947-957
Dichloroacetyl chloride (DCAC) attracted our attention as an intermediate product of the photocatalytic degradation of trichloroethylene
(TCE). The adsorption and photocatalytic reaction of DCAC on TiO2 have been investigated by FTIR spectroscopy. The influence of the surface structure of several TiO2s on the reaction mechanism was discussed in order to understand the complete degradation mechanism of TCE as well as DCAC.
DCAC was transformed into dichloroacetic acid (DCAA) on the relatively hydrophobic TiO2 surface by the small amount of the water molecules weakly adsorbed on the surface. This DCAA was degraded to phosgene, CO2, and CO during UV irradiation. For the hydrophilic TiO2, DCAC was mainly transformed into the dichloroacetate anion. UV irradiation allowed this species to produce chloroform in
addition to phosgene, CO2, and CO. It is suggested that DCAC easily reacts with the Ti–OH group on the hydrophilic TiO2 and forms the bidentate titanium chelate of dichloroacetate, which efficiently degrades into chloroform. 相似文献
13.
TiO2/MCM-41 composites with various titania content were prepared by loading titania into the mesopores of MCM-41 molecular sieves by sol-gel method, and were used as photocatalysts to degrade Rhodamine B (RhB) and phenol. The efficiency of organic contaminants removal was increased significantly compared with pure TiO2. Ti/Si ratio, namely, the content of TiO2 was determined by ICP-AES method. TiO2/MCM-41 composites were characterized by X-ray diffraction, UV-Vis absorption spectroscopy and N2 adsorption techniques. Experimental results demonstrated that most of the RhB was adsorbed instead of being degradated by TiO2/MCM-41 due to the large specific surface area of MCM-41, while most of phenol was degradated. It turned out that the TiO2/MCM-41 with the highest Ti/Si ratio of 0.8220 (wt) had the highest catalytic activity. 相似文献
14.
Fengxiang Li Junlin Xie De Fang Feng He Kai Qi Pijun Gong 《Research on Chemical Intermediates》2017,43(10):5413-5432
A series of Ce–MnO x /TiO2 catalysts were prepared using a novel sol–gel template method and investigated for low-temperature selective catalytic reduction (SCR) of NO with NH3 at temperatures ranging from 353 to 473 K. The 0.07Ce–MnO x /TiO2 catalyst showed the highest activity and best resistance to SO2 poisoning. The structure and properties of the catalysts were characterized using X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), thermogravimetry (TG)–differential scanning calorimetry (DSC)–mass spectroscopy (MS), high-resolution transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller (BET) measurements, H2-temperature-programmed reduction (TPR), and NH3-temperature-programmed desorption (TPD). The superior catalytic activity of the 0.07Ce–MnO x /TiO2 catalyst was probably due to a change in the active components, an increase in surface active oxygen and surface acid sites, and lower crystallinity and larger surface area with Ce doping. Furthermore, the reduction ability also became stronger. The SO2 poisoning resistance of the 0.07Ce–MnO x /TiO2 catalyst improved because doping with Ce can effectively decrease the formation of ammonium salt on the catalyst surface and the sulfation of MnO x . In situ diffuse-reflectance infrared Fourier-transform (DRIFT) spectroscopy experiments indicated that addition of Ce could promote adsorption of NH3 and inhibit generation of some nitryl species. The SCR reactions over the catalysts mainly followed the Eley–Rideal mechanism accompanied with a partial Langmuir–Hinshelwood mechanism. 相似文献
15.
So-Eun Kim Youngjong Kang Shiao-Wei Kuo Changwoon Nah Kwang-Un Jeong 《Journal of Sol-Gel Science and Technology》2011,60(2):206-213
Epitaxially grown titanium dioxide (TiO2) nanofibers embedding single crystalline TiO2 nanowires (NWs) were successfully fabricated by electropinning poly(vinyl pyrrolidone)/ethanol solutions mixed with hydrothermally
synthesized TiO2 NWs and titanium isopropoxide precursors and subsequently calcinating the electrospun nanofibers. Utilizing scanning electron
microscopy (SEM) and transmission electron microscopy (TEM), the morphologies of TiO2 NWs and nanofibers were investigated. High resolution TEM (HR-TEM) and selected area electron diffraction (SAED) allowed
us to indentify the fact that, during the calcination process under the optimized condition, titanium isopropoxide precursors
were epitaxially crystallized on the surface of single crystalline TiO2 NWs. Based on the X-ray diffraction (XRD) experiments, it was also realized that the crystalline structure of hydrothermally
synthesized TiO2 NWs and epitaxially crystallized TiO2 nanofibers is anatase and that TiO2 composite nanofibers embedding TiO2 NWs exhibited a higher crystallinity than the pristine TiO2 nanofibers. Additionally, ultraviolet visible (UV–Vis) spectra of nanofibers indicated that optical properties of TiO2 nanofibers can be tuned by introducing the single crystalline TiO2 NWs. 相似文献
16.
Feng Tao Yingzhong Shen Yanyu Liang Hulin Li 《Journal of Solid State Electrochemistry》2007,11(6):853-858
A novel composite of Co(OH)2 and TiO2 nanotubes was synthesized by a chemical precipitation method. Co(OH)2/TiO2 nanotube composites and its microstructure were characterized by transmission electron microscopy (TEM), X-ray diffraction
pattern (XRD). The electrochemical capacitance performance of this composite was investigated by cyclic voltammetry and charge–discharge
tests with a three-electrode system in 6 M KOH solution. We synthesized different weight ratios of Co(OH)2/TiO2 nanotubes, a maximum specific capacitance of 229 F/g was obtained for the composite. Based on these tests, we propose that
TiO2 nanotubes provide the three-dimensional nanotube network structure for the composite and make the Co(OH)2 dispersed. For these reasons, the TiO2 nanotubes used as a framework for Co(OH)2 improve the utilization of Co(OH)2 greatly. 相似文献
17.
M. S. Grigor’ev N. A. Budantseva A. M. Fedoseev 《Russian Journal of Coordination Chemistry》2010,36(2):157-160
The single crystals of the Np(V) complex (NH4)[NpO2(CO3)] (I) were synthesized and studied by X-ray diffraction. At 100 K, the crystals are hexagonal, space group P63 μmc, a = 5.0734(1) Å, c = 10.9191(2) Å, V= 243.399(11) Å3, Z = 2, ρ(calcd) = 4.735 g/cm3. The absorption spectra of a crystal of I in the visible and infrared ranges were measured. 相似文献
18.
P. A. S. Moura D. P. Bezerra E. Vilarrasa-Garcia M. Bastos-Neto D. C. S. Azevedo 《Adsorption》2016,22(1):71-80
Ion-exchange with different cations (Na+, NH4 +, Li+, Ba2+ and Fe3+) was performed in binderless 13X zeolite pellets. Original and cation-exchanged samples were characterized by thermogravimetric analysis coupled with mass spectrometry (inert atmosphere), X-ray powder diffraction and N2 adsorption/desorption isotherms at 77 K. Despite the presence of other cations than Na (as revealed in TG-MS), crystalline structure and textural properties were not significantly altered upon ion-exchange. Single component equilibrium adsorption isotherms of carbon dioxide (CO2) and methane (CH4) were measured for all samples up to 10 bar at 298 and 348 K using a magnetic suspension balance. All of these isotherms are type Ia and maximum adsorption capacities decrease in the order Li > Na > NH4–Ba > Fe for CO2 and NH4–Na > Li > Ba for CH4. In addition to that, equilibrium adsorption data were measured for CO2/CH4 mixtures for representative compositions of biogas (50 % each gas, in vol.) and natural gas (30 %/70 %, in vol.) in order to assess CO2 selectivity in such scenarios. The application of the Extended Sips Model for samples BaX and NaX led to an overall better agreement with experimental data of binary gas adsorption as compared to the Extended Langmuir Model. Fresh sample LiX show promise to be a better adsorption than NaX for pressure swing separation (CO2/CH4), due to its higher working capacity, selectivity and lower adsorption enthalpy. Nevertheless, cation stability for both this samples and NH4X should be further investigated. 相似文献
19.
L. Y. Zhu W. H. Duan J. M. Xu Y. J. Zhu 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):443-448
A novel method that spent nuclear fuel is converted into nitrates with N2O4, and then nitrates are extracted with TBP in supercritical CO2 (SC-CO2), has been developed for reprocessing of spent nuclear fuel, which has a potential prospect because of its potential to decrease
generation of the secondary liquid waste. In this paper, conversion of Nd2O3 with N2O4 into its nitrate under various conditions and extraction of the conversion product with TBP in SC-CO2 were investigated. When temperature was 60–120 °C, the molar ratio of H2O to Nd2O3 was from 1 to 6, and molar ratio of N2O4 to Nd2O3 was above 8, complete conversion of Nd2O3 into its nitrate was achieved. The conversion product was characterized by thermal analysis (TG-DTA), X-ray diffraction (XRD),
Fourier transformed infrared spectroscopy (FT-IR) and Raman spectroscopy. Quantitative extraction of the conversion product
with TBP in supercritical CO2 was also achieved under experimental conditions. 相似文献
20.
Xiaobo Chen Qianwen Du Wen Yang Weiwei Liu Zhongzheng Miao Peizhi Yang 《Journal of Solid State Electrochemistry》2018,22(3):685-691
We present a simple sol-gel hydrothermal process for the fabrication of a double-layered structure composed of a TiO2 nanorod overlayer and TiO2 nanoparticle-embedded ZnO nanoflower (ZNFs@TNPs-TNRs) underlayer. The ZNFs@TNPs-TNRs was used as a photoanode in dye-sensitized solar cells (DSSCs) and their photovoltaic performance was analyzed. The ZNFs@TNPs-TNRs can enhance the adsorption of N719 dyes, charge transport, and light scattering. The cell performances can be maximized by optimizing thickness ratio and total thickness of the double-layered photoanode, and the preliminary results demonstrate that a promising power conversion efficiency (PCE) of 8.01% is determined on the DSSC with ZNFs@TNPs-TNRs anode, yielding a 28.9% enhancement in the PCE in comparison to pristine TiO2–P25 nanoparticle-based DSSC. 相似文献