共查询到20条相似文献,搜索用时 15 毫秒
1.
Bimodal mesoporous TiO2 microspheres with high photocatalytic activity were prepared by a hydrothermal method using titanium sulfate as precursor in the presence of urea. The results indicate that all prepared samples show bimodal pore-size distributions in the mesoporous region: smaller intra-aggregated pores with peak pore diameter of ca. 2 nm and larger inter-aggregated pores with peak pore diameter of ca. 12.5 nm. The molar ratio of urea to Ti(SO4)2 (Ru) has an obvious influence on the morphology, microstructure and photocatalytic activity of TiO2. With increasing Ru, specific surface areas and porosity increase, contrarily, the crystallite size and relative anatase crystallinity decrease. The photocatalytic activity first increases with Ru. At Ru = 2.0, the photocatalytic activity reaches the highest and is obviously higher than that of Degussa P25. With further increasing Ru, the photocatalytic activity decreases. The formation rate of hydroxyl radicals during photocatalysis has a positive correlation with the photocatalytic activity. 相似文献
2.
Nanocrystalline mesoporous TiO2 was synthesized by hydrothermal method using titanium butoxide as starting material. XRD, SEM, and TEM analyses revealed that the synthesized TiO2 had anatase structure with crystalline size of about 8 nm. Moreover, the synthesized titania possessed a narrow pore size distribution with average pore diameter and high specific surface area of 215 m2/g. The photocatalytic activity of synthesized TiO2 was evaluated with photocatalytic H2 production from water-splitting reaction. The photocatalytic activity of synthesized TiO2 treated with appropriate calcination temperature was considerably higher than that of commercial TiO2 (Ishihara ST-01). The utilization of mesoporous TiO2 photocatalyst with high crystallinity of anatase phase promoted great H2 production. Furthermore, the reaction temperature significantly influences the water-splitting reaction. 相似文献
3.
Jia Tang Peng Yin Xiaohui Lu Dawei Qi Yu Mao Chunhui Deng Pengyuan Yang Xiangmin Zhang 《Journal of chromatography. A》2010,1217(15):2197-2205
In this study, mesoporous TiO2 microspheres were synthesized by simple hydrothermal reaction, and successfully developed for phosphopeptides enrichment from both standard protein digestion and real biological sample such as rat brain tissue extract. The mesoporous TiO2 microspheres (the diameter size of about 1.0 μm) obtained by simple hydrothermal method were found to have a specific surface area of 84.98 m2/g, which is much larger than smooth TiO2 microspheres with same size. The surface area of mesoporous TiO2 microspheres is almost two times of commercial TiO2 nanoparticle (a diameter of 90 nm). Using standard proteins digestion and real biological samples, the superior selectivity and capacity of mesoporous TiO2 microspheres for the enrichment of phosphorylated peptides than that of commercial TiO2 nanoparticles and TiO2 microspheres was also observed. It has been demonstrated that mesoporous TiO2 microspheres have powerful potential for selective enrichment of phosphorylated peptides. Moreover, the preparation of the mesoporous TiO2 microspheres obtained by the hydrothermal reaction is easy, simple and low-cost. These mesoporous TiO2 microspheres with the ability of large scale synthesis can widely be applied for phosphorylated proteomic research. 相似文献
4.
Hongye Zhang Yun Xie Zhimin Liu Ranting Tao Zhenyu Sun Kunlun Ding Guimin An 《Journal of colloid and interface science》2009,338(2):468-473
Monodispersed TiO2 hybrid microspheres were prepared via the hydrolysis of titanium isopropoxide (TTIP) in ethanol solution containing p-aminophenylacetic acid (APA). The effects of the APA:TTIP molar ratio, water content, reaction time and reaction temperature on the morphology of the resultant spheres were investigated. The products were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. It was demonstrated that the diameters of the resultant TiO2 spheres could be tuned in the range of 380–800 nm by changing the APA:TTIP molar ratio (1:3 to 3:1) and water content (1–3 v/v%) in the reaction medium, and that increasing the APA:TTIP molar ratio led to larger TiO2 hybrid spheres while increasing the water content decreased their size. The loading content of APA in the hybrid spheres could reach 20 wt.% as they were prepared with the APA:TTIP ratio of 3:1. The possible formation mechanism of the hybrid spheres was also investigated. It was found that APA slowed down the hydrolysis rate of the titanium precursor so that resulted in the formation of the TiO2 spheres. In addition, the APA present in TiO2 spheres acted as a reducing agent to in situ convert HAuCl4 into metallic Au on the surface of the TiO2 spheres. The catalytic activity of the resultant Au/APA–TiO2 composite was examined using transfer hydrogenation of phenylacetone with 2-propanol, and it was indicated that the catalyst displayed high efficiency for this reaction. 相似文献
5.
Chloride-catalyzed oxidation of phenol in pulsed-laser irradiation titanium dioxide sols 总被引:1,自引:0,他引:1
Guozheng Li Gottfried Grabner Ruth Quint Raimund Quint Nikola Getoff 《Journal of Chemical Sciences》1991,103(3):505-511
The kinetics of photolysis of phenol in presence of two kinds of TiO2 colloid in acid aqueous solution medium was studied by transient absorption spectroscopy. The absorbance and quantum yield
of the phenoxyl radicals is strongly influenced by the chloride ions. The process of laser flash photolysis of phenol in the
presence of chloride has been discussed. 相似文献
6.
Robert Kun Sndor Tarjn Albert Oszk Torben Seemann Volker Zllmer Matthias Busse Imre Dkny 《Journal of solid state chemistry》2009,182(11):3076-3084
Nitrogen-doped TiO2 catalysts were prepared by a precipitation method. The samples were calcined at 400 °C for 4 h in air. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), low temperature N2-adsorption was used for structural characterization and UV-diffuse reflectance (UV-DR) was applied to investigate the optical properties of the as-prepared samples. It was found that microporous N-doped catalysts have solely anatase crystalline structure. Acidic treatment of the calcined samples was performed using sulfuric acid agitation. The crystalline structure remained unchanged due to surface treatment, while the porosity and the surface areas were decreased dramatically. Optical characterization of the doped catalysts showed that they could be excited by visible light photons in the 400–500 nm wavelength range (λg,1=390 nm, λg,2=510 nm). It was also established that surface treatment enhances the Vis-light absorption of the N-TiO2 powders. Finally the catalysts were tested in the photocatalytic degradation of phenol in aqueous suspensions. Two different light sources were used; one of them was a UV-rich high pressure Hg-lamp, while the other was a tubular visible light source. We found that using visible light illumination N-doped, acid treated TiO2 samples were more catalytically active than non-doped TiO2 catalysts. 相似文献
7.
Here we report on the hierarchical porous rutile TiO2 nanorod micospheres as an anode material for lithium-ion batteries. The resulting hierarchical porous rutile TiO2 nanorod microspheres possessed much higher reversible capacity, cycling stability and rate capability than nanosized rutile TiO2 previously reported in the literatures. These good electrochemical performances may be attributed to the facile diffusion of Li+ ions from outside through the porous channels into the TiO2 nanorods in the microspheres and the high electrode–electrolyte contact area offered by hierarchical porous microspheres with a large specific surface area. 相似文献
8.
The photocatalytic C-F bond cleavage in pentafluorobenzoic acid (PFBA) with TiO2-P25 using UV-C light has been investigated under different conditions. Complete cleavage of C-F is observed with TiO2-P25 under UV-C light irradiation. Oxidants such as IO4−, BrO3−, S2O82−, H2O2 and ClO3− ions enhance the defluoridation of PFBA. The order of their activities is IO4− > H2O2 > S2O82− ≈ BrO3− > ClO3−. C-F cleavage is also influenced by the addition of inorganic anions and metal ions. The defluoridation intermediates were analyzed by GC-MS technique. 相似文献
9.
Photonic crystal sensing materials have been validated that they are very sensitive to refractive index changes. Herein, three-dimensionally ordered macroporous (3DOM) (>50 nm) TiO2 inverse opal film has been fabricated by the self-assembly technique. Based on the TiO2 inverse opal film, the optical spectrometer was established for label-free immunosensor. The sensing performance of the 3DOM TiO2 was investigated using human IgG/goat anti-human IgG couple, which showed that the sensitivity of 3DOM TiO2 inverse opal film could reach to 1 μg mL−1 (equivalent to 1.5 pg mm−2) of protein concentration detection limit. The 3DOM TiO2 inverse opal has a large internal surface area, low fluorescence background and unique optical properties. These characteristics indicated the feasibility of 3DOM TiO2 inverse opal in label-free immunoassay. 相似文献
10.
SiO2/TiO2 composite microspheres with microporous SiO2 core/mesoporous TiO2 shell structures were prepared by hydrolysis of titanium tetrabutylorthotitanate (TTBT) in the presence of microporous silica microspheres using hydroxypropyl cellulose (HPC) as a surface esterification agent and porous template, and then dried and calcined at different temperatures. The as-prepared products were characterized with differential thermal analysis and thermogravimetric (DTA/TG), scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption. The results showed that composite particles were about 1.8 μm in diameter, and had a spherical morphology and a narrow size distribution. Uniform mesoporous titania coatings on the surfaces of microporous silica microspheres could be obtained by adjusting the HPC concentration to an optimal concentration of about 3.2 mmol L−1. The anatase and rutile phase in the SiO2/TiO2 composite microspheres began to form at 700 and 900 °C, respectively. At 700 °C, the specific surface area and pore volume of the SiO2/TiO2 composite microspheres were 552 and 0.652 mL g−1, respectively. However, at 900 °C, the specific surface area and pore volume significantly decreased due to the phase transformation from anatase to rutile. 相似文献
11.
以锐钛矿相TiO2溶胶为基底,采用沉淀法和液相沉积法制备了TiO2/Cu2O/Pt复合空心微球,通过改变nTi4+∶ nCu2+和H2PtCl6·6 H2O溶液的加入量对TiO2的形貌和结构进行调控,采用不同的方法对不同样品的物相及结构、微观形貌和光学性能进行了对比分析。分析结果表明,复合材料中Pt与Cu2O的引入产生协同效应,不仅在一定程度上阻止了电子-空穴的复合,还降低了禁带宽度,在可见光区域光吸收明显增强。与TiO2、Cu2O和TiO2/Cu2O光催化剂相比较,TiO2/Cu2O/Pt降解有机污染物的能力显著增强,首次光照120 min可降解93%的甲基橙(MO)溶液,4次循环后降解率为71%,具有良好的光催化稳定性能。 相似文献
12.
以锐钛矿相TiO2溶胶为基底,采用沉淀法和液相沉积法制备了TiO2/Cu2O/Pt复合空心微球,通过改变n(Ti4+)∶nCu2+和H2Pt Cl6·6H2O溶液的加入量对TiO2的形貌和结构进行调控,采用不同的方法对不同样品的物相及结构、微观形貌和光学性能进行了对比分析。分析结果表明,复合材料中Pt与Cu2O的引入产生协同效应,不仅在一定程度上阻止了电子-空穴的复合,还降低了禁带宽度,在可见光区域光吸收明显增强。与TiO2、Cu2O和TiO2/Cu2O光催化剂相比较,TiO2/Cu2O/Pt降解有机污染物的能力显著增强,首次光照120 min可降解93%的甲基橙(MO)溶液,4次循环后降解率为71%,具有良好的光催化... 相似文献
13.
BaF2 nanocrystals doped with 5.0 mol% Eu3+ has been successfully synthesized via a facile, quick and efficient ultrasonic solution route employing the reactions between Ba(NO3)2, Eu(NO3)3 and KBF4 under ambient conditions. The product was characterized via X-ray powder diffraction (XRD), scanning electron micrographs (SEM), transmission electron microscopy (TEM), high-resolution transmission electron micrographs (HRTEM), selected area electron diffraction (SAED) and photoluminescence (PL) spectra. The ultrasonic irradiation has a strong effect on the morphology of the BaF2:Eu3+ particles. The caddice-sphere-like particles with an average diameter of 250 nm could be obtained with ultrasonic irradiation, whereas only olive-like particles were produced without ultrasonic irradiation. The results of XRD indicate that the obtained BaF2:Eu3+ nanospheres crystallized well with a cubic structure. The PL spectrum shows that the BaF2:Eu3+ nanospheres has the characteristic emission of Eu3+ 5D0-7FJ (J=1-4) transitions, with the magnetic dipole 5D0-7F1 allowed transition (590 nm) being the most prominent emission line. 相似文献
14.
Yi Xie Xiujian Zhao Yuanzhi Li Qingnan Zhao Xuedong Zhou Qihua Yuan 《Journal of solid state chemistry》2008,181(8):1936-1942
This article describes the preparation of mesoporous rod-like F-N-codoped TiO2 powder photocatalysts with anatase phase via a sol-gel route at the temperature of 373 K, using cetyltrimethyl ammonium bromide (CTAB) as surfactant. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectra (UV-vis DRS). The results showed that the photocatalysts possessed a homogeneous pore diameter and a high surface area of 106.3-160.7 m3 g−1. The increasing CTAB reactive concentration extended the visible-light absorption up to 600 nm. The F-N-codoped TiO2 powders exhibited significant higher adsorption capacity for methyl orange (MO) than that of Degussa P25 and showed more than 6 times higher visible-light-induced catalytic degradation for MO than that of P25. 相似文献
15.
Jikai YangXintong Zhang Changhua WangPanpan Sun Lingling WangBin Xia Yichun Liu 《Solid State Sciences》2012,14(1):139-144
Ultrasonic spray pyrolysis method was used to prepare Nb-doped TiO2 porous microspheres with an average diameter of 500 nm for solar photocatalytic applications. The effect of Nb-doping on morphology, structure, surface area, as well as spectral absorption properties of TiO2 microspheres was investigated with SEM, TEM, XRD, Raman spectra, BET, and UV-Vis absorption spectra. The Nb-doping decreased the grain size of TiO2 porous microsphere, and influenced its surface area and pore size distribution dependent on the doping concentration, but changed negligibly the morphology and size of TiO2 microspheres. Moreover, the Nb-doping was observed to extend the spectral absorption of TiO2 into visible spectrum, and the absorption onset was red-shifted for about 88 nm at a doping level of 5% compared to pristine TiO2 microspheres. Under solar or visible irradiation, Nb-doped TiO2 microspheres showed higher photocatalytic activity for methylene blue degradation compared with TiO2 microspheres, which could be ascribed to the extended light absorption range and the suppression of electron-hole pair recombination. 相似文献
16.
Nano-composite of Fe-doped anatase TiO2 nanocrystals loaded on the hollow glass microbeads was prepared by co-thermal hydrolysis deposition and calcining treatment. The adherence of TiO2 mesoporous layers to the surfaces of hollow glass microbeads prevented the aggregation of TiO2 nanoparticles and benefited to their catalytic activity. The doping of Fe ions makes the absorption edge of the TiO2 based nano-composite red-shifted into the visible region. An effective photodegradation of the methyl orange aqueous solution was achieved under visible light (λ>420 nm) irradiation, revealing the potential applicability of such nano-composite in some industry fields, such as air and water purifications. 相似文献
17.
Cosima D. Calvano Ole N. Jensen Carlo G. Zambonin 《Analytical and bioanalytical chemistry》2009,394(5):1453-1461
A new micro-solid phase extraction (μ-SPE) procedure based on titanium dioxide microcolumns was developed for the selective
extraction of phospholipids (PLs) from dairy products before matrix-assisted laser desorption ionization time-of-flight mass
spectrometry (MALDI-TOF-MS) analysis. All the extraction steps (loading, washing, and elution) have been optimized using a
synthetic mixture of PLs standard and the procedure was subsequently applied to food samples such as milk, chocolate milk
and butter. The whole method demonstrated to be simpler than traditional approaches and it appears very promising for a rapid
PLs screening and characterization also in biological matrices. 相似文献
18.
A novel absorbent was prepared by dimercaptosuccinic acid chemically modifying mesoporous titanium dioxide and was employed as the micro-column packing material for simultaneous separation/preconcentration of inorganic arsenic and antimony species. It was found that both trivalent and pentavalent of inorganic As and Sb species could be adsorbed quantitatively on dimercaptosuccinic acid modified TiO2 within a pH range of 4–7, and only As(III) and Sb(III) could be quantitatively retained on the micro-column within a pH range of 10–11 while As(V) and Sb(V) were passed through the micro-column without the retention. Based on this fact, a new method of flow injection on-line micro-column separation/preconcentration coupled to inductively coupled plasma optical emission spectrometry was developed for simultaneous speciation of trace inorganic arsenic and antimony in natural waters. Under the optimized conditions, an enrichment factor of 10 and sampling frequency of 10 h− 1 were obtained with on-line mode. The detection limits of As(III), As(V), Sb(III), and Sb(V) are 0.53, 0.49, 0.77 and 0.71 ng mL− 1 for on-line mode and as low as 0.11, 0.10, 0.15 and 0.13 ng mL− 1 for off-line mode due to its higher enrichment factor (50), respectively. The relative standard deviations of two modes are less than 6.7% (C = 20 ng mL− 1, n = 7). The concentration ratio of lower oxidation states/higher oxidation states changing from 1:10 to 10:1 has no obvious effect on the recoveries of As(III) and Sb(III). In order to validate the developed method, two certified reference materials of GSBZ5004-88 and GBW(E)080545 water sample were analyzed and the determined values are in good agreement with the certified values. The proposed method was successfully applied to the simultaneous speciation of inorganic arsenic and antimony in natural waters. 相似文献
19.
Xiaotong Zhang Jing Xu Guangwei Bai Lei Wang 《Journal of solid state chemistry》2010,183(6):1394-1399
Using composite surfactant templates, polyoxyethylene (20) oleyl ether (Brij98) and cetyl trimethyl ammonium bromide (CTAB), as structure-directing agents, N and La co-doped mesoporous TiO2 complex photocatalysts were synthesized successfully. The micromorphology of co-doped mesoporous TiO2 samples was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FT-IR), energy-dispersive X-ray spectrometer (EDS) and N2 adsorption-desorption measurements. The results indicated that the complex photocatalyst prepared with a molar ratio of Brij98:CTAB=1:1 showed a uniform pore size of ca. 7 nm and a high specific surface area (SBET) of 279.0 m2 g−1, and exhibited the highest photocatalytic activity for degradation of papermaking wastewater under ultra-violet light irradiation. The chemical oxygen demand (CODcr) percent degradation was about 73% in 12 h and chroma percent degradation was 100% in 8 h. 相似文献
20.
Nano-sized rod-like titanium dioxide (TiO2) filled rigid poly(vinyl chloride) (PVC) nanocomposites were prepared by using injection-molding method. Vicat, Charpy impact and tensile tests as well as thermogravimetric and dynamic mechanical analyses were used to characterize the structure and properties of the nanocomposites. The results showed that nano-TiO2 could improve Vicat softening temperature and also improve thermal stability of PVC during the stages of dehydrochlorination and formation of carbonaceous conjugated polyene sequences, which can be ascribed to restriction of the nanoparticles on the segmental relaxation as being evidenced by raises in glass transition and β-relaxation temperatures of PVC upon filling TiO2. Addition of TiO2 nanoparticles less than 40 phr (parts per hundreds of resin) could significantly improve impact strength of the composites while the TiO2 agglomeration at high contents leads to a reduction in impact toughness. 相似文献