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1.
Fabrication and efficient photocatalytic degradation of methylene blue over CuO/BiVO4 composite under visible-light irradiation 总被引:1,自引:0,他引:1
Hai-qing Jiang Hiromitsu Endo Hirotaka Natori Masayuki Nagai Koichi Kobayashi 《Materials Research Bulletin》2009,44(3):700-706
CuO/BiVO4 composite photocatalysts were prepared by solution combustion synthesis method and impregnation technique. X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scan electron microscopy and UV-vis diffusion reflectance spectra were used to identify the physical properties and photophysical properties of CuO/BiVO4 composite photocatalysts. The photocatalysts exhibit the enhanced photocatalytic properties for degradation of methylene blue under visible-light (λ > 420 nm). The mechanism of improved photocatalytic activity is also discussed. 相似文献
2.
Indium oxide and indium-cobalt oxide thin films have been successfully prepared by direct UV irradiation of amorphous films of β-diketonate complexes on Si(1 0 0) substrates. Deposited films were characterized by X-ray diffraction, Auger electron spectroscopy and X-ray photoelectron spectroscopy. The surface morphology of the films, examined by atomic force microscopy and scanning electron microscopy, revealed that mixed indium-cobalt oxide films are much smoother than In2O3 films, with rms surface roughness of 7.24 and 26.1 nm, respectively. 相似文献
3.
Liaoyuan Xia Mingqiu Zhang Minzhi Rong Kunkun Guo Yunchu Hu Yiqiang Wu Tibor Czigany 《Composites Science and Technology》2012
Wormhole-like mesoporous tungsten carbide/carbon (WC/C) composites can be prepared by an easy method that combines emulsion processing with triblock copolymer self-assembly strategy, followed by a high-temperature carbothermal reduction. X-ray diffraction, transmission electron microscopy, X-ray spectroscopy, thermogravimetric analysis and N2 sorption techniques were employed to characterize the mesoporous WC/C composites. The results show that the resultant materials have a wormhole-like mesostructure containing nanoscale (∼40 nm) tungsten carbide particles, and high surface areas (up to 314.9 cm2/g). It is proposed that a general assemble procedures are responsible for the wormhole-like mesoporous WC/C composites. 相似文献
4.
Lei Zhao 《Materials Research Bulletin》2009,44(5):984-188
Carbon Nanotube-Neodymium Oxide (CNT-Nd2O3) composite was prepared by using acid treated carbon nanotubes (CNTs) and neodymium nitrate in the presence of sodium dodecyl sulfate and ammonia liquid. Techniques of transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and differential thermal analysis (DTA) are used to characterize the morphology, structure, composition and catalytic property of the CNT-Nd2O3 composite. The experimental results show that the Nd2O3 nanoparticles, which have an average diameter of about 30-40 nm, are loaded on the surface of carbon nanotube. Compared with pure Nd2O3 nanorods, the CNT-Nd2O3 composite can catalyze the thermal decomposition of ammonium perchlorate more effectively. The sampling methods of the experimental samples made a difference on the catalytic experiment results, and the best catalytic result was obtained when de-ionized water served as the solvent of ammonium perchlorate. 相似文献
5.
Dye Coumarin 151 was postgrafted into the rodlike SBA-15 mesoporous materials, which were synthesized by a direct hydrothermal synthesis method and further modified by an organic silane with a terminal amino group. Characterization by powder X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy, photoluminescence and scanning electron microscopy were carried out. Small-angle X-ray diffraction and N2 adsorption-desorption characterizations showed that these dye containing materials remained as ordered mesostructures and the pore size was from 6 nm for blank sample to 3.6 nm for postgrafting sample. PL characterization of composite samples exhibited optical properties with different dye concentrations. The characterization showed the existence of Coumarin 151 in the channels of SBA-15 and the composite materials with novel optical properties enabled possible applications in optical sensing and electron acceptors. 相似文献
6.
Polystyrene (core)-titania (shell) composite spheres consisting were readily prepared by a sol-gel process of titanium tetrabutoxide (TBOT) in a mixed solvent of ethanol/acetonitrile (3:1, v/v). Smooth and homogeneous titania coatings formed when the mixed solvent was dehydrated by anhydrous sodium sulfate. The thickness and surface roughness of titania coating increase with increase of the TBOT concentration. By adjusting the TBOT concentration in the range of 5.8-29.0 mM, the size of titania-coated PS spheres could be varied from 990 to 1125 nm. Calcination at elevated temperature gave dense, homogeneous, robust shells of anatase titania. The sizes of titania hollow spheres are 11.3-16.9% smaller than those of the titania-coated PS spheres as a result of calcination-induced shrinkage. The composite and hollow spheres were characterized by scanning electron microscopy, transmission electron microscopy and electron diffraction measurements. These core-shell organic-inorganic spheres and hollow ceramic spheres may have wide applications in catalysts, adsorbents, lightweight fillers, capsules, etc. 相似文献
7.
Yanbao Fu 《Materials Letters》2009,63(22):1946-1948
SnO2/multi-walled carbon nanotube (MWCNT) composite was prepared via a diffusion method. Firstly the MWCNT was sonicated in a filtrate which was derived from a tin dichloride solution mixed with AgNO3 solution. Then the SnO2/MWCNT composite was prepared whereby, after calcination in N2 atmosphere, the salts inside the MWCNT decomposed to SnO2. The resulting composite was characterized by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, which indicated that SnO2 had infiltrated into the MWCNT and filled the interior. The subsequent evaluation of the electrochemical performance in lithium ion batteries showed that the SnO2/MWCNT composite had a reversible discharge capacity of 505.9 mAh?g− 1 after 40 cycles, as compared to 126.4 mAh?g− 1 for pure nano-SnO2. 相似文献
8.
The multiwalled carbon nanotubes (MWCNTs) produced by catalytic chemical vapor deposition (CCVD) route were heat treated to 2500 °C to improve the structure, morphology and purity level. The process has lead to substantial reduction in the catalytic impurity along with an improved thermal stability and degree of graphitization of these tubes that can possibly lead to its better utilization in various applications. The structural changes following heat treatment have been correlated using various characterization techniques such as Raman spectroscopy, X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, thermo gravimetric analysis and electron paramagnetic resonance spectroscopy. The electrical and mechanical properties of the polymer composites prepared with heat treated MWCNT show improved properties over the one prepared by as produced MWCNT. 相似文献
9.
The synthesis of microsized carbon spheres supporting the semiconductor platinum diphosphide, PtP2, was conducted by the thermal decomposition of an organometallic precursor. This novel reaction was carried out using the reaction under autogenic pressure at elevated temperature (RAPET) method by dissociating Pt(PPh3)4 at 1000 °C. The product was characterized using methods of electron microscopy (scanning electron microscope (SEM), transmission electron microscope (TEM), selected area energy dispersive spectroscopy (SAEDS), elemental analyzer (EA) and energy dispersive X-ray analysis (EDX)) and powder-XRD. Transmission electron microscope images indicate that the particle size of the nanoparticles of PtP2 coated on the carbon spheres is 50 nm. 相似文献
10.
B. Rajesh 《Materials Research Bulletin》2008,43(3):682-692
The influence of nature and concentration of acid species on surface morphology and physicochemical properties of titania particles synthesized by direct thermal hydrolysis of titanium tetrachloride was investigated. The acids used were hydrochloric acid, nitric acid, sulfuric acid, and perchloric acid with a concentration of 3 M. Thermal hydrolysis of titanium tetrachloride in hydrochloric acid and perchloric acid with molar ratios of [H+]/[Ti4+] = 0.5, 1.0, 1.5, and 2.0, respectively, was used to study the effect of acid concentration. The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and thermogravimetric analysis. Characterization of the samples by X-ray diffraction studies revealed the influence of acid species on the phase transformation of titania. Samples prepared by hydrochloric acid, nitric acid, and perchloric acid formed rutile phase with rhombus primary particles, while sulfuric acid resulted in anatase phase with flake-shaped primary particles. Transmission electron microscopy and dynamic light scattering results confirmed the nanosized titania particles and the agglomeration of primary particles to form secondary particles in spherical shape. The particle size of titania prepared using perchloric acid was smaller than those prepared with other acid sources. A direct correlation between [H+]/[Ti4+] ratio and particle size of titania was observed. 相似文献
11.
A modified solution combustion approach was used for the first time in the preparation of nanosize zirconia toughened alumina (ZTA) composite. ZTA-1 with an average particle size of ∼37 nm was prepared using corresponding metal nitrates and urea. ZTA-2 with an average particle size of <10 nm was prepared by using mixture of fuels such as ammonium acetate, urea and glycine. The products formed were characterised by powder X-ray diffractometry, Transmission electron microscopy and BET surface area analysis. By using mixture of fuels, the energetics of the combustion reaction and eventually the properties of the combustion product have been changed. A series of combustion reactions were carried out to optimise the fuel ratio combinations required to obtain <10 nm ZTA particles. The microstructure of ZTA consisted of crystallites of Al2O3 and ZrO2 both of which were nanocrystalline as evident from TEM. 相似文献
12.
Ultrafine fluorite type Dy2Zr2O7 nanocrystals with cubic structure were fabricated at relatively low temperature by stearic acid method (SAM) using zirconium(IV) butoxide and dysprosium nitrate as raw materials, stearic acid as solvent and dispersant. The fabrication process was monitored by thermogravimetric analysis and differential thermal analysis (TG-DTA) and Fourier transform infrared spectroscopy (FT-IR). The obtained products were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectrometer (EDS) and UV-vis absorption spectroscopy. A single phase of Dy2Zr2O7 with high crystallinity was formed at 800 °C. The interplanar distances measured from the HRTEM image were 0.284 and 0.256 nm, respectively, coinciding with the theoretical values. 相似文献
13.
Mesoporous indium hydroxide nanorods were successfully synthesized by a mild one-step one-pot method. The obtained samples were characterized by X-ray diffraction, transmission electron microscopy with selected area electron diffraction, N2 adsorption, ultraviolet-visible absorption and photoluminescence, respectively. Transmission electron microscopy showed that there were some pores in the samples, which were mainly composed of rod-like shapes with length of 300 nm and diameter of 90 nm. N2 adsorption/desorption measurements confirmed that the prepared powder was mesoporous with average pore diameter of 3.1 nm. The ultraviolet-visible absorption spectroscopy analysis indicated that the band gap energy of the samples was 5.15 eV. Photoluminescence spectrum showed that there were two strong emissions under ultraviolet light irradiation. The growth mechanism of indium hydroxide nanorods and the role of cetyltrimethyl ammonium bromide were also discussed. 相似文献
14.
Synthesis and electrochemical performance of LiV3O8/carbon nanosheet composite as cathode material for lithium-ion batteries 总被引:1,自引:0,他引:1
Nurul Hayati Idris M.M. RahmanJia-Zhao Wang Zhi-Xin ChenHua-Kun Liu 《Composites Science and Technology》2011,71(3):343-349
To improve the rate capability and cyclability of LiV3O8 cathode for Li-ion batteries, LiV3O8 was modified by forming LiV3O8/carbon nanosheet composite. The LiV3O8/carbon nanosheet composite was successfully achieved via a hydrothermal route followed by a carbon coating process. The morphology and structural properties of the samples were investigated by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). TEM observations demonstrated that LiV3O8/carbon composite has a very flat sheet-like morphology, with each nanosheet having a smooth surface and a typical length of 400-700 nm, width of 200-350 nm, and thickness of 10-50 nm. Each sheet was surrounded by a thick layer of amorphous carbon. Electrochemical tests showed that the LiV3O8/carbon composite cathode features long-term cycling stability (194 mAh g−1 at 0.2 C after 100 cycles) and excellent rate capability (110 mAh g−1 at 5 C, 104 mAh g−1 at 10 C, and 82 mAh g−1 at 20 C after 250 cycles). Electrochemical impedance spectra (EIS) indicated that the LiV3O8/carbon composite electrode has very low charge-transfer resistance compared with pristine LiV3O8, indicating the enhanced ionic conductivity of the LiV3O8/carbon composite. The enhanced cycling stability is attributed to the fact that the LiV3O8/carbon composite can prevent the aggregation of active materials, accommodate the large volume variation, and maintain good electronic contact. 相似文献
15.
Thin films of nanocrystalline SnS2 on glass substrates were prepared from solution by dip coating and then sulfurized in H2S (H2S:Ar = 1:10) atmosphere. The films had an average thickness of 60 nm and were characterized by X-ray diffraction studies, scanning electron microscopy, EDAX, transmission electron microscopy, UV-vis spectroscopy, and Raman spectroscopy. The influence of annealing temperature (150-300 °C) on the crystallinity and particle size was studied. The effect of CTAB as a capping agent has been tested. X-ray diffraction analysis revealed the polycrystalline nature of the films with a preferential orientation along the c-axis. Optical transmission spectra indicated a marked blue shift of the absorption edge due to quantum confinement and optical band gap was found to vary from 3.5 to 3.0 eV with annealing temperature. Raman studies indicated a prominent broad peak at ∼314 cm−1, which confirmed the presence of nanocrystalline SnS2 phase. 相似文献
16.
ZnFe2O4/α-Fe2O3 composite hollow nanospheres were successfully fabricated via a facile one-pot solvothermal method, utilizing polyethylene glycol as soft template. X-ray diffraction and scanning electron microscopy analysis revealed that the prepared nanospheres with cubic spinel and rhombohedra composite structure had a uniform diameter of about 370 nm, and the hollow structure could be further confirmed by transmission electron microscopy. Energy dispersive X-ray, X-ray photoelectron spectroscopy and Fourier transform infrared techniques were also applied to characterize the elemental composition and chemical bonds in the hollow nanospheres. The ZnFe2O4/α-Fe2O3 composite hollow nanospheres show attractive light absorption property for potential applications in electronics, optics, and catalysis. 相似文献
17.
The formation of magnetite nanoparticles on the sidewalls of multi-walled carbon nanotubes 总被引:1,自引:0,他引:1
Linear polyethyleneimine (PEI) was used as a non-covalent functionalizing agent to modify multi-walled carbon nanotubes (MWCNTs). Fe3O4 nanoparticles were then formed along the sidewalls of the as-modified MWCNTs through a simple solvothermal method. X-ray diffraction, Fourier transform infrared spectrometry, transmission electron microscopy, and vibrating sample magnetometry were used to characterize the MWCNT/Fe3O4 nanocomposites. Results indicated that Fe3O4 nanoparticles with diameters ranging from 50 to 200 nm were attached to the surface of the MWCNTs by electrostatic interaction. PEI was found to improve the electrical conductivity of the MWCNT/Fe3O4 nanocomposites. The magnetic saturation value of these magnetic nanocomposites was 61.8 emu g−1. These magnetic MWCNT/Fe3O4 nanocomposites are expected to have wide applications in bionanoscience and technology. 相似文献
18.
A novel and facile approach for the preparation of exfoliated/delamination kaolinite was reported in this study. Kaolinite was mechanochemically activated by grinding with dimethylsulfoxide in a globe mill for different periods of time, and then the activated samples were treated for several hours at 120 °C to obtain the precursors of kaolinite. The resulting materials were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The experimental data indicated that the clay layers were well exfoliated/delamination under mechanochemical effect in a significantly short intercalation time. The expansion of the basal spacing (d0 0 1) of raw kaolinite by 0.40 nm pointed out that the hydrogen bonds between adjacent kaolinite layers were partially broken as a result of the intercalation with dimethylsulfoxide. 相似文献
19.
Sourav Chakraborty Jürgen Pionteck Beate Krause Susanta Banerjee Brigitte Voit 《Composites Science and Technology》2012
Commercial Udel® poly(ether sulfone) (PSU) was filled with three different commercially available multiwalled carbon nanotubes (MWCNTs) by small scale melt mixing. The MWCNTs were as grown NC 7000 and two of its derivatives prepared by ball milling treatment. One of them was unmodified (NC 3150); the other was amino modified (NC 3152). The main difference beside the reactivity was the reduced aspect ratio of NC 3150 and NC 3152 caused by ball milling process. All PSU/MWCNT composites with similar filler content were prepared under fixed processing conditions and comparative analysis of their electrical and mechanical properties were performed and were correlated with their microstructure, characterized by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A non-uniform MWCNT dispersion was observed in all composites. The MWCNTs were present in form of agglomerates in the size of 10–60 μm whereas the deagglomerated part was homogeneously distributed in the PSU matrix. The differences in the agglomeration states correlate with the variations of properties between different PSU/MWCNT composites. The lowest electrical percolation threshold of 0.25–0.5 wt.% was observed for the shortened non-functionalized MWCNT composites and the highest for amine-modified MWCNT composites (ca. 1.5 wt.%). The tensile behavior of the three composites was only slightly altered with CNT loading as compared to the pure PSU. However, the elongation at break showed a reduction with MWCNT loading and the reduction was least for composite with best MWCNT dispersion. 相似文献
20.
SiO2/Al2O3 composite microspheres with SiO2 core/Al2O3 shell structure and high surface area were prepared by depositing Al2O3 colloid particles on the surface of monodispersed microporous silica microspheres using a simple electrostatic attraction and heterogeneous nucleation strategy, and then calcined at 600 °C for 4 h. The prepared products were characterized with differential thermal analysis and thermogravimetric analysis (DTA/TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and X-ray photoelectron spectroscopy (XPS). It was found that uniform alumina coating could be deposited on the surface of silica microspheres by adjusting the pH values of the reaction solution to an optimal pH value of about 6.0. The specific surface area and pore volume of the SiO2/Al2O3 composite microspheres calcined at 600 °C were 653 m2 g−1 and 0.34 ml g−1, respectively. 相似文献