共查询到20条相似文献,搜索用时 31 毫秒
1.
AbstractTitanium dioxide (TiO2) was doped with a nonmetalic element, boron (B), and the boron doped TiO2 (B-TiO2) was combined with polyaniline (Pani) through an in-situ polymerization technique. The photocatalytic activity of the prepared samples was monitored by the degradation of methylene blue under UV light irradiation. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to reveal the effect of boron doping on the crystalline and chemical structure of the photocatalyst, respectively. The morphological and elemental compositional characteristics of the samples were evaluated using field emission scaning electron microscopy (FE-SEM) and energy dispersive x-ray analysis. The optical band gap energy of the prepared samples was obtained by UV-Visible (UV-Vis) spectroscopy. B-TiO2 exhibited enhanced photocatalytic performance compared to the undoped photocatalyst. Furthermore, compared with TiO2 and B-TiO2, Pani/B-TiO2 displayed superior photocatalytic activity. The composite achieved almost 26% methylene blue degradation within 150?minutes. Although the boron doping enhanced the crystallinity of TiO2 slightly, it did not affect the morphology. FTIR confirmed the presence of tri-coordinated interstitial boron in the Ti–O–B bonds. The UV-Vis spectra displayed a red shift with the incorporation of the boron atoms. The incorporation of the boron atoms in the TiO2 crystal structure are suggested to promote the separation of the photoinduced electron-hole pairs, a possible reason for the enhanced photocatalytic activity. B-TiO2 and its composite with polyaniline could be considered as a promising photocatalyst to remove organic dyes from the wastewater. 相似文献
2.
In G-rich DNA, it is well known that the form changes from single-strand DNA to G-quadruplex due to cations. In this study, we analyze the diffusion coefficient and fluorescence intensity obtained by fluorescence correlation spectroscopy for short G-rich DNA of the (G3T1)4 sequence labeled as 5-Carboxytetramethylrhodamine (TAMRA) with variation of the K+ ion concentration. At a K+ ion concentration of more than 200 mM, the single-strand DNA was changed to the G-quadruplex. The size of the G-quadruplex decreased to 86% than the size of the single strand DNA at K+ ion concentration of 0 M. The size of the G-quadruplex and the fluorescence intensity of TAMRA attached to the DNA were constant with an increase in the K+ ion concentration between 200 and 800 mM. This means that the size of the DNA and the fluorescence intensity of the TAMRA are not affected by the K+ ion concentration at the G-quadruplex structure because the binding structure of DNA and TAMRA dye leads to stability at a concentration of less than 100 mM K+. Based on our short G-rich DNA results, longer G-rich DNA is analyzed for the diffusion coefficient of the DNA and the fluorescence intensity variation of fluorescence dye attached to the DNA. 相似文献
3.
S. S. El-Deen A. M. Hashem A. E. Abdel Ghany S. Indris H. Ehrenberg A. Mauger C. M. Julien 《Ionics》2018,24(10):2925-2934
Anatase TiO2 nanoparticles were prepared by a simple sol-gel method at moderate temperature. X-ray powder diffraction (XRD) and Raman spectroscopy revealed the exclusive presence of anatase TiO2 without impurities such as rutile or brookite TiO2. Thermogravimetric analysis confirmed the formation of TiO2 at about 400 °C. Particle size of about 20 nm observed by transmission electron microscopy matches well with the dimension of crystallites calculated from XRD. The electrochemical tests of the sol-gel-prepared anatase TiO2 show promising results as electrode for lithium-ion batteries with a stable specific capacity of 174 mAh g?1 after 30 cycles at C/10 rate. The results show that improvement of the electrochemical properties of TiO2 to reach the performance required for use as an electrode for lithium-ion batteries requires not only nanosized porous particles but also a morphology that prevents the self-aggregation of the particles during cycling. 相似文献
4.
P.?Hájková P.??patenka J.?Krumeich P.?Exnar A.?Kolouch J.?Matou?ek P.?Ko?í 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):189-193
This paper deals with photocatalytic activity of silver treated TiO2 films. The TiO2 films were deposited on glass substrates by plasma enhanced chemical vapor deposition (PECVD) in a vacuum reactor with radio
frequency (RF) low temperature plasma discharge in the mixture of oxygen and titanium isopropoxide vapors (TTIP). The depositions
were performed under different deposition conditions. Subsequently, the surface of TiO2 films was modified by deposition of silver nanoparticles. Photocatalytic activity of both silver modified and unmodified
TiO2 films was determined by decomposition of the model organic matter (acid orange 7). Selected TiO2 samples were used for tests of antibacterial activity. These tests were performed on Gram-negative bacteria Escherichia coli. The results clearly proved that presence of silver clusters resulted in enhancement of the photocatalytic activity, which
was up to four times higher than that for pure TiO2 films. 相似文献
5.
Leonid Dolgov Valter Kiisk Valter Reedo Siim Pikker Ilmo Sildos Jaak Kikas 《Central European Journal of Physics》2011,9(2):542-546
Composite material based on a TiO2 matrix doped with Sm3+ ions and co-doped with silver was investigated. Samarium ions together with nano- and micro-aggregates of silver were incorporated
into the titanium alkoxide during the sol-gel process. Samarium ions were excited either directly (λ
exc = 488 nm) or through the TiO2 host (λ
exc = 355 nm). It was revealed that samarium fluorescence (λ
exc = 488 nm) in gelled TiO2 films is enhanced by up to 20 times in the vicinity of silver inclusions. Sensitizing and plasmonic mechanisms of enhancement
in Sm3+ fluorescence are discussed. 相似文献
6.
Hai Wang Yong Liu Minyi Zhong Hongmei Xu Hong Huang Hui Shen 《Journal of nanoparticle research》2011,13(5):1855-1863
Various TiO2 nanomaterials, such as nanosheets, nanoflowers, and nanowires were directly self assembled on titanium substrate on a large
scale under hydrothermal conditions. The morphology of the formed TiO2 nanomaterials could be easily tuned by varying the experimental parameters of temperature, reaction time, and the NaOH concentration.
A possible formation mechanism was suggested on the basis of the shape evolution of TiO2 nanostructures by SEM images in combination with XRD patterns of as-grown samples. The optical properties of TiO2 nanosheets, nanoflowers, and nanowires were characterized by reflectance spectroscopy. The studies revealed that the absorption
capability of visible light is obviously different for TiO2 with different morphologies. Moreover, TiO2 nanosheets exhibited better light trapping than TiO2 nanoflowers and TiO2 nanowires due to their unique nanostructure. 相似文献
7.
T. V. Sviridova L. Yu. Sadovskaya A. I. Kokorin E. A. Konstantinova V. E. Agabekov D. V. Sviridov 《Russian Journal of Physical Chemistry B, Focus on Physics》2017,11(2):348-353
The thin-film photocatalysts TiO2/MoO3 and TiO2/MoO3:V2O5 obtained by a combination of sol–gel and sintering techniques were studied using the photooxidation of probing dyes, EPR spectroscopy, X-ray diffraction analysis, and electron microscopy. It was shown that due to charge accumulation caused by UV irradiation, these photocatalysts retain their oxidative activity and ability for self-sterilization in the dark for a long time after irradiation was terminated (up to 5 h for TiO2/MoO3:V2O5). 相似文献
8.
TiO2 Nano rods can be used as dye-sensitized solar cells, various sensors and photocatalysts. These nanorods are synthesized by
a hydrothermal corrosion process in NaOH solution at 200°C using TiO2 powder as the source material. In the present work, the synthesis of TiO2 nanorods in anatase, rutile and Ti7O13 phases and synthesis of TiO2 nanorods by incorporating SiO2 dopant, using the sol–gel method and alkaline corrosion are reported. The morphologies and crystal structures of the TiO2 nanorods are characterized using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and
X-ray diffraction (XRD) study. The obtained results show not only an aggregation structure at high calcination temperatures
with spherical particles but also Ti–O–Si bonds having four-fold coordination with oxygen in SiO4 − . 相似文献
9.
A precursor of TiO2–LiCo1/3Ni1/3Mn1/3O2 was prepared by electrostatic self-assembly method. The final product was obtained by heating the precursor at 400–450 °C
for 4–6 h in air. X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and
electrochemical tests were used to examine the structural, morphology, elementary valence, and electrochemical characteristics.
XRD indicated that the TiO2-coated material can be indexed by α-NaFeO2 layered structure, which belongs to hexagonal-type space group R3m. XPS results confirmed the existence of TiO2 compound on the surface of the coated sample. The SEM image showed that the material had spherically porous morphology with
the uniform size about 6 μm. The initial charge–discharge capacity of the TiO2-coated LiCo1/3Ni1/3Mn1/3O2 material was 168.8/160.0 mAh/g. After 60 cycles, the discharge capacity of the TiO2-coated LiCo1/3Ni1/3Mn1/3O2 sample was 147.0 mAh/g, and the coulombic efficiency was 94.0%. Compared with the uncoated sample, the electrochemical performance
of TiO2-coated LiCo1/3Ni1/3Mn1/3O2 was improved. 相似文献
10.
M. Malligavathy S. Iyyapushpam S. T. Nishanthi D. Pathinettam Padiyan 《Journal of nanoparticle research》2017,19(4):144
Visible light Bi2O3/TiO2 nanocomposites are successfully prepared with different dosages of Bi2O3 by hydrothermal process. All the as-prepared samples are characterized by X-ray diffraction (XRD), scanning and transmission electron microscopes (SEM and TEM), Brunauer-Emmett-Teller analysis (BET), N2 adsorption-desorption measurement, and UV-Vis diffuse reflectance spectra (DRS). XRD and Raman spectra reveal the anatase phase of both TiO2 and Bi2O3/TiO2 nanocomposites. X-ray diffraction patterns demonstrate that the bismuth ions did not enter into the lattice of TiO2, and Bi2O3 is extremely dispersive on the surface of TiO2 nanoparticles. The incorporation of Bi2O3 in TiO2 leads to the spectral response of TiO2 in the visible light region and efficient separation of charge carriers. The enhanced visible light activity is tested by the photocatalytic degradation of methyl orange under light illumination, and the performance of Bi2O3/TiO2 nanocomposites are superior than that of pure TiO2 which is ascribed to the efficient charge separation and transfer across the Bi2O3/TiO2 junction. Bi2O3/TiO2 nanocomposite (20 mg) loaded with 0.25 of Bi2O3 dispersed in 50 ml of 5 ppm methyl orange solution exhibited the highest photocatalytic activity of 98.86% within 240 min of irradiation, which is attributed to the low band gap, high surface area, and the strong interaction between Bi2O3 and TiO2. 相似文献
11.
The equilibration kinetics for polycrystalline TiO2 was monitored during prolonged oxidation at 1,323 K and p(O2)=75 kPa using the measurements of the electrical conductivity and thermoelectric power. The determined kinetic data indicate
the presence of two kinetics regimes; the Regime I (rapid kinetics) and the Regime II (slow kinetics). The prolonged oxidation
of TiO2 is considered in terms of the formation of Ti vacancies at the surface and their subsequent transport into the bulk. This
effect, also observed for TiO2 single crystal, allows to obtain p-type TiO2 without the incorporation of acceptor-type foreign ions into the TiO2 lattice.
This project was performed as part of the University of New South Wales Research and Development programme on solar-hydrogen. 相似文献
12.
Hao Cheng Xiujian Zhao Xiaotao Sui Yuli Xiong Jiang Zhao 《Journal of nanoparticle research》2011,13(2):555-562
CdS quantum dot (Qd)-sensitized TiO2 nanotube array photoelectrode is synthesised via a two-step method on tin-doped In2O3-coated (ITO) glass substrate. TiO2 nanotube arrays are prepared in the ethylene glycol electrolyte solution by anodizing titanium films which are deposited
on ITO glass substrate by radio frequency sputtering. Then, the CdS Qds are deposited on the nanotubes by successive ionic
layer adsorption and reaction technique. The resulting nanotube arrays are characterized by scanning electron microscopy,
X-ray diffraction (XRD) and UV–visible absorption spectroscopy. The length of the obtained nanotubes reaches 1.60 μm and their
inner diameter and wall thickness are around 90 and 20 nm, respectively. The XRD results show that the as-prepared TiO2 nanotubes array is amorphous, which are converted to anatase TiO2 after annealed at 450 °C for 2 h. The CdS Qds deposited on the TiO2 nanotubes shift the absorption edge of TiO2 from 388 to 494 nm. The results show that the CdS-sensitized TiO2 nanotubes array film can be used as the photoelectrode for solar cells. 相似文献
13.
Monte Carlo simulations were carried out on amorphous titanium dioxide (TiO2) for both bulk and hydroxylated nanoparticles with particle sizes ranging from 1 to 10 nm. The potential developed by the Matsui and Akaogi (MA) was used to model the interatomic interactions of TiO2 in both cases (bulk and nanoparticles). Besides, Angular and Morse potentials proposed by the Tether, Cormack, Du et. al. (TCD) were introduced to model the interactions of hydroxyl groups on the TiO2 surfaces, i.e., the Ti-O-H groups with an experimental and theoretical angles of 125 o . The bulk system was developed using periodic boundary conditions. The TiO2 nanoparticles were extracted by applying a spherical cut section in the bulk TiO2 melt structure to obtain the required size. Free valences on the nanoparticle surfaces were saturated via additional hydroxyl groups and then quenched to 300 K under free boundary conditions. The bulk and surface properties of the nanoparticles were calculated at 300 K and zero pressure and characterized via radial distribution functions, bond angle distributions, bond distances, coordination numbers, OH group concentrations and radial density profiles. In addition, to understand the difference in properties of amorphous hydroxylated TiO2 nanoparticles and bulk amorphous TiO2, a comparative study was done at the same thermodynamic conditions. The study shows that the bulk properties of amorphous hydroxylated TiO2 nanoparticles are strongly size-dependent and different from those of the bulk TiO2. As expected, increasing the particle size leads to an approach of the particle’s bulk properties to the bulk properties of the (quasi) infinite system. The size effects show that decreasing the particle size results in increasing the surface effects and surface OH group concentrations. Accordingly, small-sized TiO2 nanoparticles have higher surface OH group concentrations and larger surface effects than large-sized TiO2 nanoparticles. Larger surface effects result significant changes in their bond angles, bond distances, and coordination numbers. The simulation results of the surface properties reveal that the surface titanium atoms in the TiO2 nanoparticles have the capability of accommodating up to 5 hydroxyl groups. The mean surface hydroxyl group density of the amorphous TiO2 spherical nanoparticles is estimated to be around 8.1/nm 2, which lies in the range of 8–16/nm 2, found by experimental and other simulation studies. Details of the modelling, simulations results and the study are presented in this paper. 相似文献
14.
K. Prasad Lily K. Kumari K.P. Chandra K.L. Yadav S. Sen 《Applied Physics A: Materials Science & Processing》2007,88(2):377-383
Polycrystalline (Na0.5Sb0.5)TiO3 was prepared using a high-temperature solid-state reaction method. An XRD analysis indicated the formation of a single-phase
monoclinic structure. Complex impedance studies revealed the presence of grain boundary effects from 300 °C onwards. Also,
the dielectric relaxation in the system was found to be of a non-Debye type. The ac conductivity data were used to evaluate
the density of states at the Fermi level, the minimum hopping length and activation energy of the compound. The dc electrical
and thermal conductivities of grain and grain boundary have been assessed. The correlated barrier hopping model was found
to successfully explain the mechanism of charge transport in (Na0.5Sb0.5)TiO3.
PACS 72.20.Ee; 77.22.Ch; 77.22.Gm; 77.84.Dy; 81.05.Je 相似文献
15.
P. Calandra D. Lombardo A. Pistone V. Turco Liveri S. Trusso 《Journal of nanoparticle research》2011,13(11):5833-5839
In this paper a novel hybrid approach to synthesise composite nanoparticles is presented. It is based on the laser ablation
of a bulk target (Yb) immersed in a reversed micellar solution which contains nanoparticles of a different host material (TiO2 nanoparticles) previously synthesised by chemical method. This approach thus exploits the advantages of the chemical synthesis
through reversed micellar solution (size control, nanoparticle stabilisation), and of the laser ablation (“clean” synthesis,
no side reactions). Central role is played by the microscopic processes controlling the deposition of the ablated Yb atoms
onto the surface of TiO2 nanoparticles which actually behave as nucleation seeds. The structural features of the resulting Yb@TiO2 composite nanoparticles have been studied by Transmission Electron Microscopy, whereas their peculiar optical properties
have been explored by UV–Vis spectroscopy and steady-state fluorescence. Results consistently show the formation of Yb and
TiO2 glued nanodomains to form nearly spherical and non-interacting nanoparticles with enhanced photophysical properties. 相似文献
16.
Chienchih Chen Hsunling Bai Sue-min Chang Chungliang Chang Walter Den 《Journal of nanoparticle research》2007,9(3):365-375
The nitrogen doped (N-doped) titanium dioxide (TiO2) photocatalyst was prepared by the atmospheric-pressure plasma-enhanced nanoparticles synthesis (APPENS) process operated
under normal temperature, i.e. the dielectric barrier discharge plasma process. The N2 carrier gas is dissociated in the AC powered nonthermal plasma environment and subsequently doped into the TiO2 photocatalyst that was capable of being induced by visible light sources. The APPENS process for producing N-doped TiO2 showed a higher film deposition rate in the range of 60–94 nm/min while consuming less power (<100 W) as compared to other
plasma processes reported in literatures. And the photocatalytic activity of the N-doped TiO2 photocatalyst was higher than the commercial ST01 and P25 photocatalysts in terms of toluene removals in a continuous flow
reactor. The XPS measurement data indicated that the active N doping states exhibited N 1s binding energies were centered
at 400 and 402 eV instead of the TiN binding at 396 eV commonly observed in the literature. The light absorption in the visible
light range for N-doped TiO2 was also confirmed by a clear red shift of the UV-visible spectra. 相似文献
17.
Hexagonal and cubic Li0.5TiO2 particles have been fabricated through magnesiothermic reduction of Li2TiO3 particles in a temperature range of 600 to 640 °C. The prolonged reduction time results in lattice transition from hexagonal to cubic structure of Li0.5TiO2. Their microstructures, valance state, chemical composition, as well as electrochemical performance as anode candidates for lithium ion batteries have been characterized and evaluated. The hexagonal Li0.5TiO2 exhibits better electrochemical activity compared with the cubic one. Further, the carbon-coated hexagonal Li0.5TiO2 displays improved electrochemical performance with initial reversible capacity of 176.6 mAh g?1 and excellent cyclic behavior except capacity fading in the initial 10 cycles, which demonstrate a novel anode candidate for long lifetime lithium ion batteries. 相似文献
18.
Lead-free Na0.5Bi0.5TiO3 (NBT) and (1 ? x)Na0.5Bi0.5TiO3 + xBaTiO3 with x = 0.1 and 0.2 (where x = 0.1 and 0.2 are named as NBT1 and NBT2, respectively), (1 ? y)Na0.5Bi0.5TiO3 + yBa0.925Nd0.05TiO3 with y = 0.1 and 0.2 (where y = 0.1 and 0.2 are named as NBT3 and NBT4, respectively)-based relaxor ferroelectric ceramics were prepared using the sol-gel method. The crystal structure was investigated by X-ray diffraction (XRD) at room temperature (RT). The XRD patterns confirmed the presence of the rhombohedral phase in all the samples. The electrical properties of the present NBT-based samples were investigated by complex impedance and the modulus spectroscopy technique in the temperature range of RT–600 °C. The AC conductivity was found to increase with the substitution of Ba2+ ions to the NBT sample whereas it significantly decreased with the addition of Nd3+ ions. The more anion vacancies in Ba-added samples and the lower anion vacancies in Nd-added samples were found to be responsible for higher and lower conductivities, respectively. 相似文献
19.
Yanhui Hou Yechen Wang Huili Yuan Hang Chen Guowei Chen Junhai Shen Liangchao Li 《Journal of nanoparticle research》2016,18(11):343
Heterogeneous photo-Fenton SiO2/Fe3O4/C@TiO2 (SFCT) catalyst with a core-multishell structure and a diameter of about 550 nm was successfully prepared and was characterized by scanning electron microscopy (SEM), TEM, XRD, Raman, and Fourier transform infrared (FT-IR). The results illustrated that anatase TiO2 coexisted with rutile TiO2, in which the anatase phase was the main crystal phase. In addition, the catalytic activity of SFCT catalyst had been evaluated in the catalytic degradation on p-nitrophenol (PNP). The influence factors on the PNP degradation, including SFCT component ratio (m SFC/ m TiO2), H2O2 dosage, solution pH, and PNP concentration, had been investigated. And the contrast experiments about the photo-Fenton catalytic mechanism revealed that the SFCT-2 catalyst possessed a superior activity in the neutral environment due to the optimal activity matching between Fe3O4 and TiO2, and it exhibited the stable catalytic performance after five successive recycles. Therefore, the SFCT-2 catalyst had a promising application for the photo-Fenton degradation of organic contaminant. 相似文献
20.
G. Valverde-Aguilar J. A. García-Macedo V. Rentería-Tapia M. Aguilar-Franco 《Applied Physics A: Materials Science & Processing》2011,103(3):659-663
In this work, amorphous and crystalline TiO2 films were synthesized by the sol–gel process at room temperature. The TiO2 films were doped with gold nanoparticles. The films were spin-coated on glass wafers. The crystalline samples were annealed
at 100°C for 30 minutes and sintered at 520°C for 2 h. All films were characterized using X-ray diffraction, transmission
electronic microscopy and UV-Vis absorption spectroscopy. Two crystalline phases, anatase and rutile, were formed in the matrix
TiO2 and TiO2/Au. An absorption peak was located at 570 nm (amorphous) and 645 nm (anatase). Photoconductivity studies were performed on
these films. The experimental data were fitted with straight lines at darkness and under illumination at 515 nm and 645 nm.
This indicates an ohmic behavior. Crystalline TiO2/Au films are more photoconductive than the amorphous ones. 相似文献