共查询到20条相似文献,搜索用时 31 毫秒
1.
Guohui Chang Yonglan Luo Wenbo Lu Fang Liao Xuping Sun 《Journal of nanoparticle research》2011,13(7):2689-2695
In this article, we have reported on the synthesis of ultra-highly concentrated (5.88 M), well-stable Ag nanoparticles (AgNPs).
The AgNPs were formed by hydrothermal heat treatment of an aqueous solution of poly [(2-ethyldimethylammonioethyl methacrylate
ethyl sulfate)-co-(1-vinylpyrrolidone)] (PQ11), a kind of cationic polyeletrolyte, in the presence of AgNO3 powder at 170 °C, without the additional step of introducing other reducing agents and protective agents. Transmission electron
microscopy (TEM) observations reveal that the as-formed AgNPs mainly consist of small nanoparticles about 10 nm in diameter.
Most importantly, it was found that such dispersion can form stable films on bare electrode surfaces and the AgNPs contained
therein still exhibit notable catalytic performance for reduction of hydrogen peroxide (H2O2). This H2O2 sensor has a fast amperometric response time of less than 3 s. Its linear range is estimated to be from 0.1 to 60 mM (r = 0.993), and the detection limit is estimated to be 1.6 μM at a signal-to-noise ratio of 3. 相似文献
2.
Sen Liu Lei Wang Jingqi Tian Wenbo Lu Yingwei Zhang Xiaodan Wang Xuping Sun 《Journal of nanoparticle research》2011,13(10):4731-4737
Polymer-free Pt/graphene nanosheet (GN) composites have been rapidly prepared by a one-step microwave-assisted reduction method, carried out by ethylene glycol reduction of H2PtCl6 in a graphene oxide suspension. Several analytic techniques including UV?Cvis spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy have been used to characterize the resulting Pt/GN composites. It suggests that such composites exhibit good catalytic activity toward methanol oxidation. 相似文献
3.
Novel g-C3N4 modified Bi2O3 (g-C3N4/Bi2O3) composites were synthesized by a mixing-calcination method. The samples were characterized by thermogravimetry (TG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), UV–vis diffuse reflection spectroscopy (DRS), photoluminescence (PL) and photocurrent-time measurement (PT). The photocatalytic activity of the composites was evaluated by degradation of Rhodamine B (RHB) and 4-chlorophenol (4-CP) under visible light irradiation (>400 nm). The results indicated that the g-C3N4/Bi2O3 composites showed higher photocatalytic activity than that of Bi2O3 and g-C3N4. The enhanced photocatalytic activity of the g-C3N4/Bi2O3 composites could be attributed to the suitable band positions between g-C3N4 and Bi2O3. This leads to a low recombination between the photogenerated electron–hole pairs. The proposed mechanism for the enhanced visible-light photocatalytic activity of g-C3N4/Bi2O3 composites was proven by PL and PT analysis. 相似文献
4.
A photoelectron and energy-loss spectroscopy study of Ti and its interaction with H2, O2, N2 and NH3
《Surface science》1986,167(1):207-230
A unified electron spectroscopic study of polycrystalline Ti and its interaction with H2, O2, N2, and NH3 are described. Auger electron spectroscopy (AES), electron energy-loss spectroscopy (ELS), ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS) are combined to provide detailed information about the electronic structure of the titanium surface and its interaction with these adsorbates. X-ray and ultraviolet photoelectron spectra and electron energy-loss spectra are presented for the clean titanium surface, and following exposure to H2, O2, N2 and NH3. Spectral assignments are provided in each case. The electron spectra of oxygen exposed Ti and nitrogen sputtered Ti are quite similar, and are interpreted with reference to band structure calculations for TiO and TiN. Electron spectroscopy indicates essentially complete dissociative adsorption of NH3 on the clean titanium surface. 相似文献
5.
Ryosuke Nakahara Satomi Kashitani Kumi Hayakawa Yuuki Kitani Takako Yamaguchi Yoshikazu Fujita 《Journal of fluorescence》2009,19(5):769-775
A fluorophotometric method for the determination of hydrogen peroxide (H2O2) using fluorescin was developed. This method was based on the oxidative reaction of fluorescin, a colorless, non-fluorescent
lactoid fluorescein, by H2O2 to give highly fluorescein fluorescence emission. In the determination of H2O2, the calibration curve exhibited linearity over the H2O2 concentration range of 1.5–310 ng mL−1 at an emission wavelength of 525 nm with an excitation of 500 nm and with relative standard deviations (n = 6) of 2.51%, 2.48%, and 1.31% for 3.1 ng mL−1, 30.8 ng mL−1, and for 308 ng mL−1 of H2O2, respectively. The detection limit for H2O2 was 1.9 ng mL−1 six blank determinations was performed (ρ = 6). This proposed method was applied to detection of other reactive oxygen species and nitrogen species (ROS/RNS) such
as singlet oxygen (1O2), hydroxyl radical (•OH), peroxynitrite (ONOO−) etc., and it was possible to detect them with a high sensitivity. In addition, this proposed method was applied to the recovery
tests of H2O2 in calf serum, human saliva, rain water, and wheat noodles; the results were satisfactory. 相似文献
6.
F–B–S tri-doped titanium dioxide thin films on common glass were prepared by a modified sol–gel method, in which tetrabutyl
titanate (Ti(OC4H9)4) was chosen as the precursor and boric acid (H3BO3), sodium fluoride (NaF), and thiourea (N2H4CS) were employed as boron, fluorine, and sulfur sources, respectively. The microstructure and optical property were characterized
by X-ray diffraction, high-resolution field emission scanning electron microscopy, N2 adsorption–desorption isotherms, photoluminescence spectrum, and UV–Vis diffraction reflectance spectroscopy. The photocatalytic
performances were evaluated by decomposition of organic dyes in solution. The experimental results revealed that the F–B–S
tri-doped TiO2 thin film was composed of uniform round-like nano-particles with the size range of 5–8 nm. F–B–S tri-doping not only significantly promoted the UV-induced photodecomposition activities of TiO2 films but also extended the optical response of TiO2 red shift to visible light region, herein improving the visible light-induced degradation of organic dyes. The improvement
mechanism by F–B–S tri-doping was also discussed. 相似文献
7.
Jin Zhang Jiaxin Li Fereidoon S. Razavi Abdul Md. Mumin 《Journal of nanoparticle research》2011,13(5):1909-1916
A new method to produce elaborate nanostructure with magnetic and fluorescent properties in one entity is reported in this
article. Magnetite (Fe3O4) coated with fluorescent silica (SiO2) shell was produced through the one-pot reaction, in which one reactor was utilized to realize the synthesis of superparamagnetic
core of Fe3O4, the formation of SiO2 coating through the condensation and polymerization of tetraethylorthosilicate (TEOS), and the encapsulation of tetramethyl
rhodamine isothiocyanate-dextran (TRITC-dextran) within silica shell. Transmission electron microscopy (TEM), energy dispersive
X-ray (EDX) analysis, and X-ray diffraction (XRD) were carried out to investigate the core–shell structure. The magnetic core
of the core–shell nanoparticles is 60 ± 10 nm in diameter. The thickness of the fluorescent SiO2 shell is estimated at 15 ± 5 nm. In addition, the fluorescent signal of the SiO2 shell has been detected by the laser confocal scanning microscopy (LCSM) with emission wavelength (λem) at 566 nm. In addition, the magnetic properties of TRITC-dextran loaded silica-coating iron oxide nanoparticles (Fe3O4@SiO2 NPs) were studied. The hysteresis loop of the core–shell NPs measured at room temperature shows that the saturation magnetization
(M
s) is not reached even at the field of 70 kOe (7T). Meanwhile, the very low coercivity (H
c) and remanent magnetization (M
r) are 0.375 kOe and 6.6 emu/g, respectively, at room temperature. It indicates that the core–shell particles have the superparamagnetic
properties. The measured blocking temperature (T
B) of the TRITC-dextran loaded Fe3O4@SiO2 NPs is about 122.5 K. It is expected that the multifunctional core–shell nanoparticles can be used in bio-imaging. 相似文献
8.
A. E. Abdel Ghany A. M. A. Hashem H. A. M. Abuzeid A. E. Eid H. A. Bayoumi C. M. Julien 《Ionics》2009,15(1):49-59
Single phase LiCo1 − y
Ni
y
O2 (y = 0.4 and 0.5) with fine particles and high homogeneity was synthesized by “chimie douce” assisted by citric acid as the
polymeric agent and investigated as positive electrodes in rechargeable lithium batteries. The long-range and short-range
structural properties are investigated with experiments including X-ray diffraction (XRD), Fourier transform infrared spectroscopy
(FTIR), and superconducting quantum interference device magnetometry. The physicochemical properties of the powders (crystallinity,
lattice constants, grain size) have been investigated in this composition. The powders adopted the α-NaFeO2 structure as it appeared from XRD and FTIR results. Magnetic measurements shows signal at low temperature attributed to the
magnetic domains in the nanostructure sample from which we estimated that the cation mixing are 3.35 and 4.74% for y = 0.4 and 0.5 in LiCo1 − y
Ni
y
O2, respectively. LiCo0.5Ni0.5O2 cathode yields capacity (135 mAh g−1) compared to LiCo0.6Ni0.4O2 cathode (147 mAh g−1) when discharged to a cutoff voltage of 2.9 V vs. Li/Li+. Lower capacity loss and higher discharge efficiency percentage are observed for the cell of LiCo0.6Ni0.4O2 cathode. 相似文献
9.
Photoluminescence and Photoacoustic Spectroscopies of Fe3+ in the LiGa5O8–LiGaSiO4–Li5GaSi2O8 System
This report is devoted to the study of the low and room temperature photoluminescence and photoacoustic spectroscopy of the
Fe3+ impurity ion in the LiGa5O8–LiGaSiO4–Li5GaSi2O8 system. The sample was obtained by solid-state reaction between β-Ga2O3, Li2CO3, SiO2 and appropriated quantities of Fe2O3. It was investigated by X-ray diffraction to determine the formed phases and through photoluminescence, excitation and photoacoustic
spectroscopy measurements. The broad absorption and emission bands in the visible and near-infrared spectral regions presented
by that system constitute the motivation for this study. More specifically, the luminescence occurs over a large interval
of wavelengths, between 400 nm and 800 nm. 相似文献
10.
Tanju Eren Necip Atar Mehmet Lütfi Yola Hassan Karimi-Maleh Alper Tolga Çolak Asim Olgun 《Ionics》2015,21(8):2193-2199
In the present study, we report the green and one-pot synthesis of silver nanoparticles (AgNPs) on as-prepared novel polyoxometalate {[Ni2,5(Hpen)4(PW9O34)]?·?5H2O} (POM) without any reducing agent and its application as improved anode material for lithium-ion batteries (LIBs). The structure of the AgNPs involved POM (AgNPs/POM) nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The synthesized POM was also characterized by elemental analysis and thermal analysis. The electrochemical performances of the POM, AgNPs, and AgNPs/POM composites were measured for charge/discharge specific capacities at different current rates in CR2032 coin-type cells. The prepared AgNPs/POM composite showed a high specific gravimetric capacity of about 1760 mAh g?1 and long-term cycle stability. 相似文献
11.
Mohammed M. Rahman Aslam Jamal Sher Bahadar Khan Mohd Faisal 《Journal of nanoparticle research》2011,13(9):3789-3799
The production of low-dimensional nanoparticles (NPs) with appropriate surface modification has attracted increasing attention
in biological, biochemical, and environmental applications including chemical sensing, photocatalytic degradation, separation,
and purification of toxic molecules from the matrices. In this study, iron oxide NPs have been prepared by hydrothermal method
using ferric chloride and urea in aqueous medium under alkaline condition (pH 9 ~ 10). As-grown low-dimensional NPs have been
characterized by UV–vis spectroscopy, FT-IR, X-ray diffraction, Field emission scanning electron microscopy, Raman spectroscopy,
High-resolution Transmission electron microscopy, and Electron Diffraction System. The uniformity of the NPs size was measured
by the scanning electron microscopy, while the single phase of the nanocrystalline β-Fe2O3 was characterized using powder X-ray diffraction technique. As-grown NPs were extensively applied for the photocatalytic
degradation of acridine orange (AO) and electrochemical sensing of ammonia in liquid phase. Almost 50% photo-catalytic degradation
with AO was observed in the presence of UV sources (250 W) with NPs. β-Fe2O3 NP-coated gold electrodes (GE, surface area 0.0216 cm2) have enhanced ammonia-sensing performances in their electrical response (I–V characterization) for detecting ammonia in liquid phase. The performances of chemical sensor were investigated, and the results
exhibited that the sensitivity, stability, and reproducibility of the sensor improved significantly using β-Fe2O3 NPs on GE surface. The sensitivity was approximately 0.5305 ± 0.02 μAcm−2mM−1, with a detection limit of 21.8 ± 0.1 μM, based on a signal/noise ratio of 3 with short response time. 相似文献
12.
L. Ciaffoni B. L. Cummings W. Denzer R. Peverall S. R. Procter G. A. D. Ritchie 《Applied physics. B, Lasers and optics》2008,92(4):627-633
High resolution diode laser spectroscopy has been applied to the detection of hydrogen sulphide at ppm levels utilizing different
transitions within the region of the ν
1+ν
2+ν
3 and 2ν
1+ν
2 combination bands around 1.58 μm. Suitable lines in this spectral region have been identified, and absolute absorption cross
sections have been determined through single-pass absorption spectroscopy and confirmed in the Doppler linewidth regime using
cavity enhanced absorption spectroscopy (CEAS). The desire for a sensitive system potentially applicable to H2S sensing at atmospheric pressure has led to an investigation on suitable transitions using wavelength modulation spectroscopy
(WMS). The set-up sensitivity has been calculated as 1.73×10−8 cm−1 s1/2, and probing the strongest line at 1576.29 nm a minimum detectable concentration of 700 ppb under atmospheric conditions
has been achieved. Furthermore, pressure broadening coefficients for a variety of buffer gasses have been measured and correlated
to the intermolecular potentials governing the collision process; the H2S–H2S dimer well depth is estimated to be 7.06±0.09 kJ mol−1. 相似文献
13.
BaCe0.7Ta0.1Y0.2O3−
δ
(BCTY) and BaCe0.8Y0.2O3−
δ
(BCY) were synthesized by solid-state reaction method at 1,300 °C for 20 h. After being exposed in 3% CO2 + 3% H2O + 94% N2 at 700 °C for 20 h, the BCTY exhibited adequate chemical stability against carbonations while BCY decomposed into BaCO3 and CeO2. The BCTY showed the similar thermal expansion behavior to BCY from room temperature to 1,000 °C in air. The BCTY displayed
a conductivity of 0.007 S/cm at 700 °C in humid hydrogen, lower than that of BCY (0.009 S/cm). A fuel cell with 10-μm thick
BCTY membrane prepared through an all-solid-state process exhibited 1.004 V for OCV, 330 mW/cm2 for maximum output at 700 °C, respectively. Short-term test shows that the fuel cell performance does not degrade after 20 h. 相似文献
14.
Ma?gorzata A. Ma?ecka Ulrich Burkhardt Dariusz Kaczorowski Marcus P. Schmidt Daniel Goran Leszek K?piński 《Journal of nanoparticle research》2009,11(8):2113-2124
The structure and phase evolution of nanocrystalline Ce1−
x
Ln
x
O2−
x/2−δ (Ln = Yb, Lu, x = 0 − 1) oxides upon heating in H2 was studied for the first time. Up to 950 °C the samples were single-phase, with structure changing smoothly with x from fluorite type (F) to bixbyite type (C). For the Lu-doped samples heated at 1100 °C in the air and H2, phase separation into coexisting F- and C-type structures was observed for ~0.40 < x < ~0.70 and ~0.25 < x < ~0.70, respectively. It was found also that addition of Lu3+ and Yb3+ strongly hinders the crystallite growth of ceria during heat treatment at 800 and 950 °C in both atmospheres. Valency of
Ce and Yb in Ce0.1Lu0.9O1.55−δ and Ce0.95Yb0.05O1.975−δ samples heated at 1100 °C was studied by XANES and magnetic measurements. In the former Ce was dominated by Ce4+, with small contribution of Ce3+ after heating in H2. In the latter, Yb existed exclusively as 3+ in both O2 and H2. 相似文献
15.
Adolfo Franco Thiago Eduardo Pereira Alves Emília Celma de Oliveira Lima Eloisa da Silva Nunes Vivien Zapf 《Applied Physics A: Materials Science & Processing》2009,94(1):131-137
For the first time nanocrystalline magnetic particles of Mg
x
Fe(3−x)O4 with x ranging from 0.5 to 1.5 have been synthesized by a combustion reaction method using iron nitrate Fe(NO3)3.9H2O, magnesium nitrate Mg(NO3)2.6H2O, and urea CO(NH2)2 as fuel without intermediate decomposition and/or calcining steps. X-ray diffraction patterns of all systems showed broad
peaks consistent with cubic inverse spinel structure of MgFe2O4. The absence of extra reflections in the diffraction patterns of as-prepared materials ensures the phase purity. The mean
crystallite sizes determined from the prominent (311) peak of the diffraction using Scherrer’s equation and transmission electron
microscopy micrographs were c.a. 40 nm with spherical morphology. Fourier transform infrared spectra of the as-prepared material
showed traces of organic and metallic salt by-products; however, these could be removed by washing with deionized water. Typical
hysteresis curves were obtained for all specimens in magnetic field up to 14 T between 4 and 340 K. The saturation magnetization
was 48.3 emu/g and 31.3 emu/g, 44.8 emu/g, and 28.4 emu/g for x=1.0 and 0.8 at 4 K and 340 K, respectively. The saturation magnetization, M
s
, of nanoparticles of the MgFe2O4 specimen is about 50% higher when compared to the bulk. The enhanced magnetization measured in our nanoparticles MgFe2O4 specimens may be attributed to the uncompensated magnetic moment of iron ions between the A- and B-sites, i.e., changes in
the inversion factor. Our magnetization results of MgFe2O4 specimens are comparable to the existing data for the same compound but with different particle size and prepared by different
synthesis methods. 相似文献
16.
Jing Kong Jiurong Liu Fenglong Wang Liqiang Luan Masahiro Itoh Ken-ichi Machida 《Applied Physics A: Materials Science & Processing》2011,105(2):351-354
Large-scale octahedral Fe3O4 nanocrystallines with crystalline size of 100−500 nm were synthesized by a facile solvent-thermal method for electromagnetic
wave application. The Fe3O4 nanocrystallines showed a higher saturation magnetization (M
s
) value of 86.8 emu/g and larger coercivity (H
cj
) value of 255 Oe than that of magnetite polycrystallines because of their good crystallization and dispersion. The epoxy
resin composites with 40 vol% Fe3O4 powders provided good electromagnetic wave absorption performance (RL < −20 dB) in the range of 2.0–4.3 GHz over the absorber
thicknesses of 3.5–6.8 mm. A minimum RL value of −47 dB was observed at 3.1 GHz with a thickness of 4.8 mm. 相似文献
17.
Ting-Feng Yi Li-Juan Jiang Ji Liu Ming-Fu Ye Hong-Bao Fang An-Na Zhou Jie Shu 《Ionics》2011,17(9):799-803
Powders of spinel Li4Ti5O12 (LTO) were successfully synthesized at reducing conditions by solid-state method. The structure and physical properties of
Li4Ti5O12 were examined by X-ray diffraction (XRD), Raman spectroscopy, scanning electronic microscopy (SEM), and differential capacitance,
respectively. XRD shows that both samples are single-phase spinel compounds. LTO synthesized in Ar/H2(8% mol) has a larger lattice parameter than that in Ar. SEM indicates that all of the prepared powders have the uniform,
nearly cubic structure morphology with narrow size distribution in the range of 200–300 nm. Raman spectra indicate that the
Raman bands corresponding to the Ti–O vibration has a blue shift from 674 to 680 cm−1 due to the few H2 in the synthesized condition, indicating that there is very few oxygen vacancies in the Li4Ti5O12 synthesized under Ar/H2 (8% mol). The dQ/dV vs. voltage plots reveals the redox potentials for the synthesized Li4Ti5O12-negative electrode materials. 相似文献
18.
Jianhong Wei Qi Zhang Yang Liu Rui Xiong Chunxu Pan Jing Shi 《Journal of nanoparticle research》2011,13(8):3157-3165
Polyaniline (PANI)–TiO2 nanocomposites possessing both nano and microscale structures were prepared through a facile hydrothermal route in the presence
of PANI. The nanopapilla particles were characterized by scanning electron microscopy, transmission electron microscopy, energy
dispersive X-ray analysis, X-ray photoelectron spectra, X-ray diffraction, FTIR spectra, UV–Vis spectroscopy, and N2 adsorption analysis, etc. The results show that the composites possess both nano and microscale structures. The TiO2 nanorods are dispersed on PANI with one end fixed to the surface. The photocatalytic properties of the powders were verified
by the photodegradation of gaseous acetone under UV (λ = 254 nm) and visible-light irradiation (λ > 400 nm). In fact, the photocatalytic effects exhibited by the composite particles were superior to that of pure TiO2 and P25 samples. This excellent behavior is attributed to the structural features of PANI–TiO2 microspheres and the synergistic effect between PANI and TiO2 which facilitates a larger amount of surface active sites. This in turn causes a faster charge separation and slower charge
recombination which results in a more efficient decomposition of gaseous pollutants. 相似文献
19.
This work described the sonohydrolysis of Bi(NO3)3 into Bi2O3 and simultaneous sonochemical exfoliation of graphite into graphene sheets in the alkaline environment and its electocatalytic performance towards the detection of anti-depression drug imipramine (IMPR). The ultrasound (37/80 kHz; 60 W) effectively hydrolyzed the Bi(NO3)3 into a single crystalline monoclinic phase of Bi2O3 nanotiles in the alkaline condition. And also, the sonochemical reaction condition can trigger the lamellar particles on the graphite bulk surface and allowed to exfoliated the graphite (EG) into graphene nanosheets as well. The material characterizations are done by XRD, Raman, FESEM, and HRTEM. It shows the α-Bi2O3 nanotiles along with EG nanosheets with high crystallinity and low defects. The (0 0 2) plane in XRD confirms the high crystalline nature of EG. The monoclinic stretching vibrations (90–600 cm−1) confirms the Raman modes of Bi2O3. The prepared Bi2O3-EG composites are subjected to the electrochemical determination of IMPR which revealed appreciable analytical performances. The results showed that the Bi2O3-EG exhibits better results in the 3 h sonication process. Bi2O3-EG-3 exhibited a good linear range (0.02–82.3 µM) and an acceptable limit of detection (6 nM). And also Bi2O3-EG-3 exhibits the significant tolerance limit when compared to other potential interfering compounds. 相似文献
20.
Co3O4 nanoplate/graphene sheet composites were prepared through a two-step synthetic method. The composite material as prepared was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The platelet-like morphology of Co3O4 leads to a layer-by-layer-assembled structure of the composites and a good dispersion of Co3O4 nanoplates on the surface of graphene sheets. The electrochemical characteristics indicate that the specific capacitance of the composites is 337.8 F?g?1 in comparison with the specific capacitance of 204.4 F?g?1 without graphene sheets. Meanwhile, the composites have an excellent rate capability and cycle performance. The results show that the unique microstructure of the composites enhances the electrochemical capacitive performance of Co3O4 nanoplates due to the three-dimensional network of graphene sheets for electron transport increasing electric conductivity of the electrode and providing unobstructed pathways for ionic transport during the electrochemical reaction. 相似文献