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1.
Mesoporous CuFe2O4 solid solution nanopowders with high specific surface areas were synthesized by a novel, very simple and inexpensive sol-gel route using propylene oxide as gelation agent, and used as the catalyst in low temperature CO oxidation. The samples were characterized by X-ray diffraction, N2 adsorption-desorption, thermogravimetric/differential thermal analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and temperature-programmed reduction. The results revealed that the samples have a nanocrystalline structure with crystals in the range of 10 to 25 nm, and that all the catalysts have mesoporous pores. The addition of Cu into iron oxide affected its structural and catalytic properties. The sample containing 15 mol% Cu showed the highest specific surface area and catalytic activity, and showed high catalytic stability in low temperature CO oxidation. 相似文献
2.
Silver-doped calcium phosphate nanopowders were successfully prepared by the cost-effective electrostatic spray-pyrolysis
process. The properties of the silver-doped nanopowder annealed at 500°C for 30 min were investigated through X-ray diffraction
analysis, field emission scanning electron microscope, and Fourier transform infrared spectroscopy. The silver-doped nanopowders
with 70–90 nm particle size showed an antibacterial performance against Escherichia coli. 相似文献
3.
Viktor S. Burakov Andrey V. Butsen Volker Brüser Falk Harnisch Pulat Y. Misakov Elena A. Nevar Miriam Rosenbaum Natalie A. Savastenko Nikolai V. Tarasenko 《Journal of nanoparticle research》2008,10(5):881-886
Tungsten carbide nanopowder was prepared via pulsed discharge of bulk tungsten and graphite rods immersed in pure ethanol.
The effect of discharge parameters on the characteristics of final products was investigated. Structural and morphological
characterization of nanopowder was performed by means of X-ray diffraction analysis and transmission electron microscopy.
In order to determine the feasibility of using synthesized material as an electrocatalyst, tungsten carbide nanopowder was
tested for hydrogen evolution. A correlation was found between morphology of nanoparticles, their phase composition and electrocatalytic
activity. 相似文献
4.
Mesoporous nanocrystalline NiO-Al2O3 powders with high surface area were synthesized via ultrasound assisted co-precipitation method and the potential of the selected samples as catalyst was investigated in dry reforming reaction for preparation of synthesis gas. The prepared samples were characterized by N2 adsorption (BET), X-ray diffraction (XRD), Temperature programmed reduction and oxidation (TPR, TPO) and scanning electron microscopy (SEM) techniques. The effects of pH, power of ultrasound irradiation, aging time and calcination temperature on the textural properties of the catalysts were studied. The sample prepared under specified conditions (pH10, 70 W, without aging time and calcined at 600 °C) exhibited the highest surface area (249.7 m2 g−1). This catalyst was calcined at different temperature and employed in dry reforming of methane and the catalytic results were compared with those obtained over the catalysts prepared by impregnation and co-precipitation methods. The results showed that the catalyst prepared by ultrasound assisted co-precipitation method exhibited higher activity and stability with lower degree of carbon formation compared to catalysts prepared by co-precipitation and impregnation methods. 相似文献
5.
Jae-hyun Kim Bo-hyun Lee Hansaem Kang Jaeyeal Kim Geesung Chae Inbyeong Kang In-jae Chung 《Applied Surface Science》2009,255(23):9386-9390
Ag ink was spontaneously patterned on glass substrate by using the surface energy difference of a pre-patterned octadecyltrichlorosilane (OTS) layer. Ag ink was confined into the hydrophilic area, where OTS layer was not formed. OTS layer was selectively transferred by micro-contact printing (μCP) method and significantly decreased surface energy. As a result, surface of glass substrate was separated as hydrophobic and hydrophilic with and without OTS layer, respectively. Ag line could be successfully patterned with the width of below 10 μm on the glass. The patterned Ag line was dense and abrupt on the edge and the thickness was about 0.25 μm. Ag film showed good adhesion on a glass substrate after anneal above 200 °C. The minimum resistivity was about 4 μΩ cm. 相似文献
6.
The Er3+-doped Al2O3 nanopowders have been prepared by the sol-gel method, using the aluminium isopropoxide [Al(OC3H7)3]-derived γ-AlOOH sols with addition of the erbium nitrate [Er(NO3)3·5H2O]. The five phases of γ-(Al,Er)2O3, θ-(Al,Er)2O3, α-(Al,Er)2O3, ErAlO3, and Al10Er6O24 were detected with the 0–20 mol% Er3+-doped Al2O3 nanopowders at the different sintering temperature of 600–1200°C. The average grain size was increased from about 5 to 62 nm
for phase transformation of undoped γ-Al2O3→α-Al2O3 at the sintering temperature from 600 to 1200°C. At the same sintering temperature, average grain size was decreased with
increase of the Er3+ doping concentration. Infrared absorption spectra of γ-Al2O3 and θ-Al2O3 nanopowders showed the two broad bands of 830–870 and 550–600 cm−1, the three broad bands of 830–870, 750–760, and 550–600 cm−1, respectively. The infrared absorption spectra for the α-Al2O3 nanopowder showed three characteristic bands, 640, 602, and 453 cm−1. The two characteristic bands of 669 and 418 cm−1 for Er2O3 clusters were observed for the Er3+-doped Al2O3 nanopowders when Er3+ doping concentration was increased up to 2 mol%. The 796, 788, 725, 692, 688, 669, 586, 509, 459, and 418 cm−1 are the characteristic bands of Al10Er6O24 phase. 相似文献
7.
E.M. PopenkoA.A. Gromov Yu.I. PautovaE.A. Chaplina H.-J. Ritzhaupt-Kleissl 《Applied Surface Science》2011,257(8):3641-3644
The experimental results of combustion of aluminum nanopowder (ANP) in air and AlN crystals formation process were studied. The air pressure during the combustion process significantly affected the crystals growth mechanism. Crystals with the different morphology (whiskers, hexagonal crystals, rods) were found in the condensed combustion products. 相似文献
8.
Nanosized Zn–WO3 and ZnWO4 materials have been prepared by microwave irradiation method. The physico-chemical characterization of the prepared nanomaterials was carried out by X-ray diffraction (XRD) and high resolution-scanning electron microscopy (HR-SEM) techniques. The size and shape of the ZnWO4 material can be controlled by changing the temperature. The XRD analysis revealed the formation of monoclinic phase of the calcined nanopowder. The HR-SEM images showed the sphere and plate shape particles. The electrochemical behavior of the ZnWO4 modified electrodes was investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) techniques. The synthesized material shows the pseudocapacitance. The specific capacitance of 35.70 F/g was achieved for the Zn–WO3 nanopowder. 相似文献
9.
A. Kouprine F. Gitzhofer M. Boulos A. Fridman 《Experimental Thermal and Fluid Science》2007,31(8):1005-1019
Capacitively coupled RF discharges in methane and ethane (1000–3000 Pa, 5–15 W/cm3) were used for the in-flight coating of SiO2 nanopowders (NP) with an a-C:H layer [A. Kouprine, F. Gitzhofer, M. Boulos, A. Fridman, Polymer-like C:H thin film coating of nanopowders in capacitively coupled RF discharge, Plasma Chemistry and Plasma Processing 24 (2) (2004) 189–215]. In this present work a model of the chemical kinetics of this plasma processing has been developed, based on the GRI-Mech 3.0 mechanism [G.P. Smith, D.M. Golden, M. Frenklach, Gas Research Institute, Detailed chemical reaction mechanism. Available from: ], and calculations are performed, using the Chemkin-II code. The model includes the formation of two solid phases: an amorphous C:H coating, deposited on the suspended NP, and soot, incepted in the gas phase. Non-equilibrium plasma effects are taken into account by the rates of radical species’ production, using the reference data on the “G-value”. The CH3 and H species appear to have key roles in surface activation and the nanofilm growth. The results demonstrate the competitive character of the formation of the two solid phases: the C:H coating is dominant under Tgas < 1400–1600 K, depending on the conditions, and soot commencing to dominate at higher temperatures. This division corresponds to the passage from non-thermal plasma conditions, with the dominance of single-valent radicals and solid phase growth on the substrate only, to the plasma thermalisation with the formation of two-valent radicals and v. inception of the solid phase. The results are validated experimentally by the observation of soot formation as a function of the gas temperature, by the mass spectrograph data on the gas composition after plasma reforming, and by the reference data on coating growth rates and induction times for soot formation. 相似文献
10.
Sonochemical production of tin(II) and tin(IV) sulfides is investigated. Different conditions of syntheses are examined: used solvent (ethanol or ethylenediamine), source of tin (SnCl2 or SnCl4), the molar ratio of thioacetamide to the tin source, and time of sonication. The obtained powders are characterized by the X-ray diffraction method (PXRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), and the Tauc method. Raman and FT-IR measurements were performed for the obtained samples, which additionally confirmed the crystallinity and phase composition of the samples. The influence of experimental conditions on composition (is it SnS or SnS2), morphology, and on the bandgap of obtained products is elucidated. It was found that longer sonication times favor more crystalline product. Each of bandgaps is direct and most of them show typical values – c.a. 1.3 eV for SnS and 2.4 eV for SnS2. However, there are some exceptions. Synthesized powders show a variety of forms such as needles, flower-like, rods, random agglomerates (SnS2) and balls (SnS). Using ethanol as a solvent led to powders of SnS2 independently of which tin chloride is used. Sonochemistry in ethylenediamine is more diverse: this solvent protects Sn2+ cations from oxidation so mostly SnS is obtained, while SnCl4 does not produce powder of SnS2 but Sn(SO4)2 instead or, at a higher ratio of thioacetamide to SnCl4, green clear mixture. 相似文献