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1.
In this study different conventional individual protection devices, well-qualified for submicron particles were tested for
different types of polydispersed nanoaerosols of TiO2, Pt, and graphite. The electrical mobility diameters of the generated particles are ranging from 9 to 19 nm for Pt, 9 to
90 nm for TiO2, and 15 to 90 nm for graphite. Toward this purpose, two specific test benches were used: one for the filter-based devices
which are tested under a controlled air flow, and the other one for protective clothing and gloves under diffusion and without
air flow. Different types of nanoaerosols, such as TiO2, Pt, and graphite, were generated. Electrostatic and HEPA (High Efficiency Particle Air) filters have shown the highest efficiency
for graphite nanoparticles. The main hypothesis for explaining this effect is that electrostatic forces could enhance the
graphite nanoparticles capture. Air-tight fabrics made of non-woven textile seem much more efficient in protecting workers
against Pt, and TiO2 nanoparticles than cotton and polypropylene. With regard to protective clothing, no obvious effect linked to the aerosol
type was observed. Gloves are found very efficient for TiO2 and Pt nanoaerosols. Therefore, no effect of aerosol on the protection efficiency of gloves was evidenced. 相似文献
2.
Titanium oxide nanoparticles were coated on multiwall carbon nanotubes (MWCNTs) using an atmospheric pressure chemical vapor
deposition (CVD) to achieve highly compact nanoparticles of about 5 nm on CNT structure. The CNTs with a diameter of about
50 nm were grown by plasma enhanced CVD. Gas sensitivity of the fabricated structure was investigated and compared with TiO2/CNT composite-based gas sensors. The effect of the structural interaction between the nanoparticles and the CNT wall on sensing
mechanism of the as-prepared gas sensors was investigated. Ultrasensitive gas sensors were obtained by TiO2/CNT nanostructures with strong interaction between the MWCNT and the TiO2 nanoparticles. The measurements show high chemical activity and exceptional electrical response of the as-prepared structure
being exposed to gases. Scanning and transmission electron microscopy and X-ray diffraction analysis were used to obtain structural
information. 相似文献
3.
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
4.
Fei Qi Anna Moiseev Joachim Deubener Alfred Weber 《Journal of nanoparticle research》2011,13(3):1325-1334
Anatase is the low-temperature (300–550 °C) crystalline polymorph of TiO2 and it transforms to rutile upon heating. For applications utilizing the photocatalytic properties of nanoscale anatase at
elevated temperatures (over 600 °C) the issue of phase stabilisation is of major interest. In this study, binary TiO2/SiO2 particles were synthesized by a flame aerosol process with TiCl4 and SiCl4 as precursors. The theoretical Si/Ti ratio was varied in the range of 0.7–1.3 mol/mol. The synthesized TiO2/SiO2 samples were heat treated at 900 and 1,000 °C for 3 h to determine the thermostability of anatase. Pyrogenic TiO2 P25 (from Evonik/Degussa, Germany) widely applied as photocatalyst was used as non-thermostabilized reference material for
comparison of photocatalytic activity of powders. Both the non-calcinated and calcinated powders were characterized by means
of XRD, TEM and BET. Photocatalytic activity was examined with dichloroacetic acid (DCA) chosen as a model compound. It was
found that SiO2 stabilized the material retarding the collapse of catalyst surface area during calcination. The weighted anatase content
of 85% remains completely unchanged even after calcination at 1,000 °C. The presence of SiO2 layer/bridge as spacer between TiO2 particles freezes the grain growth: the average crystallite size increased negligibly from 17 to 18 nm even during the calcination
at 1,000 °C. Due to the stabilizing effect of SiO2 the titania nanoparticles calcinated at 900 and 1,000 °C show significant photocatalytic activity. Furthermore, the increase
in photocatalytic activity with calcination temperature indicates that the titania surface becomes more accessible either
due to intensified cracking of the SiO2 layer or due to enhanced transport of SiO2 into the necks thus releasing additional titania surface. 相似文献
5.
Qi Long Mei Cai Jinru Li Huilin Rong Long Jiang 《Journal of nanoparticle research》2011,13(4):1655-1662
One of the greatest challenges in preparing TiO2-based oxygen electrodes for PEM fuel cells is increasing the electrical catalytic activity of Pt nanoparticle/TiO2 composites by improving the dispersion of Pt. This article describes a new way for improving the dispersion of Pt nanoparticles
by depositing them on TiO2 fibers and using microwave irradiation. The Pt nanoparticles used in this experiment is about 5 nm in diameter and the diameter
of TiO2 fibers could be controlled ranging from 30 to 60 nm and Pt nanoparticles still keep their size when the deposition amount
is increased on the surface of TiO2 fibers. The Pt nanoparticles were highly dispersed without agglomeration even at a weight percentage of composites as high
as 40%. The position of Pt nanoparticles located in the fiber and the composition of Pt/TiO2, which had great influence on the electric conductivity and electrical catalytic activity of the composite, could be easily
controlled. 相似文献
6.
Saeed Dadvar Hossein Tavanai Mohammad Morshed 《Journal of nanoparticle research》2011,13(10):5163-5169
This article describes the ultraviolet (UV) protection of MgO and Al2O3 nanoparticles embedded electrospun polyacrylonitrile (PAN) nanofibrous mats. UV radiation is a harmful part of sunlight and
prolonged exposure to it can cause serious skin damages. In this research, nanofibrous mats consisting of nanofibers with
different diameters containing different amounts of MgO, Al2O3, MgO Plus, and Al2O3 Plus nanoparticles were produced, and their UV-protection was measured. The specific surface area of MgO, MgO Plus, Al2O3, and Al2O3 Plus nanoparticles was 230, 600, 275, and 550 m2/g, respectively. The mean diameter of electrospun PAN nanofibers embedded with metal oxide nanoparticles was in the range
of 665–337 nm. The results showed that the UV-protection (shielding) capability of the mats strongly depends on fiber diameter;
in fact a thin mat of nanofibers has a much stronger UV-protection in comparison to a thicker mat composed of regular fibers.
UV transmission is reduced as a result of embedding MgO and Al2O3 nanoparticles in the electrospun PAN nanofibrous mats. MgO Plus and Al2O3 Plus show higher UV-protection than MgO and Al2O3. 相似文献
7.
Sarah Motshekga Sreejarani K. Pillai Suprakas S. Ray 《Journal of nanoparticle research》2011,13(3):1093-1099
Carbon nanotubes decorated with SnO2 nanoparticles were prepared by conventional and microwave-assisted wet impregnation. The composites were thoroughly characterized
by X-ray diffraction, Raman spectroscopy, BET-surface area measurement, Scanning and transmission electron microscopy. The
XRD studies revealed the formation of tetragonal phase of SnO2. The microwave method produced CNTs heavily decorated with SnO2 nanoparticles with average size 5 nm in a total reaction time of 10 min because of the rapid volumetric heating. DC conductivity
increased significantly for the nanocomposite samples when compared with the pure CNTs. In electrical conductivity properties,
sample prepared by microwave method was found to be superior to the one prepared by conventional procedure due to homogeneous
distribution of nanoparticles. 相似文献
8.
Bunthoeun Nim Paiboon Sreearunothai Atitsa Petchsuk Pakorn Opaprakasit 《Journal of nanoparticle research》2018,20(4):100
Nanofibers of polylactide (PLA)/poly(vinylpyrrolidone) (PVP) blends, loaded with TiO2 nanoparticles, have been prepared by an electrospinning method. The electrospun fiber mats were characterized by ATR-FTIR, X-ray diffraction (XRD), SEM, EDX, and UV-visible spectroscopy to examine structures, functional groups, crystallinity, surface morphology, and UV absorptivity. It is clearly observed that TiO2 particles are embedded on the filaments. All PLA-based spun fibers are completely amorphous in nature. The surface morphology of those blended with PVP is smoother and more uniform than the corresponding samples without PVP. Neat PLA fibers show a UV absorption band at around 200 nm, whereas the fibers loaded with TiO2 nanoparticles show an additional absorption band covering the 200–380-nm region. Photo-degradation of the fiber samples are conducted in phosphate buffer solution (PBS) under UVA light. The results indicate that the PVP component dissolves into the PBS solution, and the PLA matrix degrades as a function of time. The fibers are then applied as a catalytic system for epoxidation of unsaturated sunflower oil (SFO), for use as additives or plasticizers for biopolymers, employing a performic acid oxidizing agent. The fibers, especially those containing PVP, can effectively enhance the epoxidation yield of oils with a slow rate of undesirable side reactions, which break ester bonds of triglycerides to generate free fatty acids. 相似文献
9.
Terry A. Egerton Lorna M. Kessell Ian R. Tooley Liwei Wang 《Journal of nanoparticle research》2007,9(2):251-260
Photogreying, the change in brightness on UV irradiation in the absence of oxygen, of TiO2 nanoparticulate dispersions is shown to depend on the nature of the liquid, consistent with a surface reaction. Measurements
on a series of TiO2 particles (mainly 75×10 nm) dispersed in, e.g., alkyl benzoate correlate well with those on the same TiO2’s dispersed in a second liquid (e.g. propan-2-ol). Photogreying in propan-2-ol is paralleled by photocatalytic-oxidation
activity, indicating a common origin – UV-generation of charge carriers. Further, photogreying parallels Ti3+ formation. Hence, although appearance and the visible spectra of photogreyed particles both differ from those of Ti3+ in ≤10 nm colloidal TiO2, we suggest that photogreying is caused by capture of UV excited electrons to form Ti3+. Surface treatment reduces photogreying, and we speculate that differences between uncoated samples reflect differences in
the number of potentially reducible Ti’s. 相似文献
10.
Akbar Shabanikia Mehran Javanbakht Hossein Salar Amoli Khadijeh Hooshyari Morteza Enhessari 《Ionics》2015,21(8):2227-2236
In this work, Fe2TiO5 nanoparticles were used for improving the proton conductivity, and water and acid uptake of polybenzimidazole (PBI)-based proton exchange membranes. The nanocomposite membranes have been prepared using different amounts of Fe2TiO5 nanoparticles and dispersed into a PBI membrane with the solution-casting method. The prepared membranes were then physico-chemically and electrochemically characterized for use as electrolytes in high-temperature PEMFCs. The PBI/Fe2TiO5 membranes (PFT) showed a higher acid uptake and proton conductivity compared with the pure PBI membranes. The highest acid uptake (156 %) and proton conductivity (78 mS/cm at 180 °C) were observed for the PBI nanocomposite membranes containing 4 wt% of Fe2TiO5 nanoparticles (PFT4). The PFT4 composite membrane showed 380 mW/cm2 power density and 760 mA/cm2 current density in 0.5 V at 180 °C at dry condition. The above results indicated that the PFT4 nanocomposite membranes could be utilized as proton exchange membranes for high-temperature fuel cells. 相似文献
11.
In this paper, data concerning the effect of pH on the morphology of Ag–TiO2 nanocomposite during photodeposition of Ag on TiO2 nanoparticles is reported. TiO2 nanoparticles prepared by sol–gel method were coated with Ag by photodeposition from an aqueous solution of AgNO3 at various pH levels ranging from 1 to 10 in a titania sol, under UV light. The as-prepared nanocomposite particles were
characterized by UV–vis absorption spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and N2 adsorption/desorption method at liquid nitrogen temperature (−196 °C) from Brunauer–Emmett–Teller (BET) measurements. It
is shown that at a Ag loading of 1.25 wt.% on TiO2, a high-surface area nanocomposite morphology corresponding to an average of one Ag nanoparticle per titania nanoparticle
was achieved. The diameter of the titania crystallites/particles were in the range of 10–20 nm while the size of Ag particles
attached to the larger titania particles were 3 ± 1 nm as deduced from crystallite size by XRD and particle size by TEM. Ag
recovery by photo harvesting from the solution was nearly 100%. TEM micrographs revealed that Ag-coated TiO2 nanoparticles showed a sharp increase in the degree of agglomeration for nanocomposites prepared at basic pH values, with
a corresponding sharp decrease in BET surface area especially at pH > 9. The BET surface area of the Ag–TiO2 nanoparticles was nearly constant at around a value of 140 m2 g−1 at all pH from 1–8 with an anomalous maximum of 164 m2 g−1 when prepared from a sol at pH of 4, and a sharp decrease to 78 m2 g−1 at pH of 10. 相似文献
12.
A. Jaworek A. Krupa M. Lackowski A.T. Sobczyk T. Czech S. Ramakrishna S. Sundarrajan D. Pliszka 《Journal of Electrostatics》2009,67(2-3):435-438
Electrospraying and electrospinning processes were employed for the production of nanocomposite material of polymer nanofibers blended with nanoparticles. The diameter of polymer nanofibers made of PVC, PSU or nylon was smaller than 500 nm. Metal oxide nanoparticles of TiO2, MgO, and Al2O3 of the size 20–100 nm suspended in methanol were deposited on the polymer nanofibers. Three configurations of electrospray/electrospun nozzles used for the nanocomposite production were tested: 1. simultaneous electrospraying during the electrospinning process, 2. electrospraying onto the same rotating drum after the electrospinning is completed, and 3. electrospraying onto the electrospun mat removed from the drum and placed onto a heated table. 相似文献
13.
Polyaniline-modified tin oxide and tin oxide nanoparticles were synthesized using a solution route technique. The obtained
pristine products were characterized with X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and
optical absorption spectroscopy. Thermogravimetric analysis results showed that the polyaniline-modified SnO2 nanoparticles exhibit higher thermal stability than the SnO2 nanoparticles. Scanning electron microscopy analysis on the as-synthesized powders showed spherical particle in the range
of 50–100 nm. 相似文献
14.
This paper aims to study fabrication and characterization of silver/titanium oxide composite nanoparticle through sonochemical process in the presence of ethylene glycol with alkaline solution. By using ultrasonic irradiation of a mixture of silver nitrate, the dispersed TiO2 nanoparticle in ethylene glycol associated with aqueous solution of sodium oxide yields Ag/TiO2 composite nanoparticle with shell/core-type geometry. The powder X-ray diffraction (XRD) of the Ag/TiO2 composites showed additional diffraction peaks corresponding to the face-centered cubic (fcc) structure of silver crystallization phase, apart from the signals from the cores of TiO2. Transmission electron microscopy (TEM) images of Ag/TiO2 composites, which average particle size is roughly 80 nm, reveal that the titanium oxide coated by Ag nanoparticle with a grain size of about 2–5 nm. Additionally, the formation of silver nanoparticles on TiO2 was monitored by ultraviolet visible light spectrophotometer (UV–Vis). As measured the optical absorption spectra of as-synthesized Ag nanoparticle varying with time, the mechanism of surface formatting silver shell on the cores of TiO2 could be explored by autocatalytic reaction; the conversion of Ag particle from silver ion is 98% for the reaction time of 1000 s; and the activity energy of synthesizing Ag nanoparticles on TiO2 is 40 kJ/mol at temperature ranging from 5 to 25 °C. Hopefully, this preliminary investigation could be used for mass production of composite nanoparticles assisted by ultrasonic chemistry in the future. 相似文献
15.
An increasing energy demand and environmental pollution create a pressing need for clean and sustainable energy solutions.
TiO2 semiconductor material is expected to play an important role in helping solve the energy crisis through effective utilization
of solar energy based on photovoltaic devices. Dye-sensitized solar cells (DSSCs) are potentially lower cost alternative to
inorganic silicon-based photovoltaic cells. In this study, we report on the fabrication of DSSCs from anodic TiO2 nanotubes (NT) powder, produced by rapid breakdown potentiostatic anodization of Ti foil in 0.1 M HClO4 electrolyte, as photoanode. TiO2 NT powders with a typical NT outer diameter of approximately 40 nm, wall thickness of approximately 8–15 nm, and length of
about 20–25 μm, have been synthesized. The counter electrode was made by electrodeposition of Pt from an aqueous solution
of 5 mM H2PtCl6 onto fluorine-doped tin oxide (FTO) glass substrate. The above front-side illuminated DSSCs were compared with back-side
illuminated DSSCs fabricated from anodic TiO2 NTs that were grown on the top of Ti foil as photoanode. The highest cell efficiency was 3.54% under 100 mW/cm2 light intensity (1 sun AM 1.5G light, Jsc = 14.3 mA/cm2, Voc = 0.544 V, FF = 0.455). To the best of our knowledge, this is the first report on the fabrication of DSSC from anodic
TiO2 NTs powder. The TiO2/FTO photoanodes were characterized by FE-SEM, XRD, and UV–Visible spectroscopy. The catalytic properties of Pt/FTO counter
electrodes have been examined by cyclic voltammetry. 相似文献
16.
Kamlesh Pandey Mrigank Mauli Dwivedi Mridula Tripathi Markandey Singh S. L. Agrawal 《Ionics》2008,14(6):515-523
Development and characterisation of polyethylene oxide (PEO)-based nanocomposite polymer electrolytes comprising of (PEO-SiO2): NH4SCN is reported. For synthesis of the said electrolyte, polyethylene oxide has been taken as polymer host and NH4SCN as an ionic charge supplier. Sol–gel-derived silica powder of nano dimension has been used as ceramic filler for development
of nanocomposite electrolytes. The maximum conductivity of electrolyte ∼2.0 × 10−6 S/cm is observed for samples containing 30 wt.% silica. The temperature dependence of conductivity seems to follow an Arrhenius-type,
thermally activated process over a limited temperature range. 相似文献
17.
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
18.
Osama A. Fouad Abd El Rahman S. Khder Qilin Dai M. Samy El-Shall 《Journal of nanoparticle research》2011,13(12):7075-7083
Nanostructured zinc oxide (ZnO) nanobelts and aluminum oxide (Al2O3) nanoribbons have been grown successfully from the vapor phase. XRD results confirmed the purity and the high quality of
the formed crystalline materials. TEM images showed that ZnO nanostructures grew in the commonly known tetrapod structure
with nanobelts separated from the tetrapods with an average width range of 10–30 nm and a length of about 500 nm. Al2O3 nanostructures grew in the form of nanoribbons with an average width range of 20–30 nm and a length of up to 1 μm. The catalytic
oxidation of CO gas into CO2 gas over the synthesized nanostructures is also reported. Higher catalytic activity was observed for Pd nanoparticles loaded
on the ZnO nanobelts (100% conversion at 270 °C) and Al2O3 nanoribbons (100% conversion at 250 °C). The catalytic activity increased in the order Cu < Co < Au < Pd for the metal-loaded
nanostructures. The preparation methods could be applied for the synthesis of novel nanostructures of various materials with
novel properties resulting from the different shapes and morphologies. 相似文献
19.
V. V. Hoang H. Zung N. H.B. Trong 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):515-524
Structural properties of amorphous TiO2 spherical nanoparticles have
been studied in models with different sizes of 2 nm, 3 nm, 4 nm and 5 nm under
non-periodic boundary conditions. We use the pairwise interatomic potentials
proposed by Matsui and Akaogi. Models have been obtained by cooling from the
melt via molecular dynamics (MD) simulation. Structural properties of an
amorphous nanoparticle obtained at 350 K have been analyzed in detail
through the partial radial distribution functions (PRDFs), coordination
number distributions, bond-angle distributions and interatomic distances.
Moreover, we show the radial density profile in a nanoparticle. Calculations
show that size effects on structure of a model are significant and that if
the size is larger than 3 nm, amorphous TiO2 nanoparticles have a
distorted octahedral network structure with the mean coordination number
ZTi-O ≈6.0 and ZO-Ti ≈3.0 like those observed in the
bulk. Surface structure and surface energy of nanoparticles have been
obtained and presented. 相似文献
20.
Many types of plastic containers have been used for the storage of food. In the present study, diamond-like carbon (DLC)/titanium oxide (TiO2) multilayer thin films were deposited on polypropylene (PP) to prevent flavour retention and to remove flavour in plastic containers.For the flavour removal test, two types of multilayer films were prepared, DLC/TiO2 films and DLC/TiO2/DLC films. The residual gas concentration of acetaldehyde, ethylene, and turmeric compounds in bottle including the DLC/TiO2-coated and the DLC/TiO2/DLC-coated PP plates were measured after UV radiation, and the amount of adsorbed compounds to the plates was determined. The percentages of residual gas for acetaldehyde, ethylene, and turmeric with the DLC/TiO2 coated plates were 0.8%, 65.2% and 75.0% after 40 h of UV radiation, respectively. For the DLC/TiO2/DLC film, the percentages of residual gas for acetaldehyde, ethylene and turmeric decreased to 34.9%, 76.0% and 85.3% after 40 h of UV radiation, respectively. The DLC/TiO2/DLC film had a photocatalytic effect even though the TiO2 film was covered with the DLC film. 相似文献