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1.
Two types of molybdenum–carbon nanotubes and molybdenum treated carbon nanotubes/titania composites were prepared using a
sol–gel method. These composites were characterized comprehensively by the Brauer–Emett–Teller (BET) surface area, scanning
electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), transmission electron microscopy
(TEM) and UV-vis absorption spectroscopy. It was found that the photocatalytic degradation of a methylene blue solution could
be attributed to the combined effects caused by the photo-degradation of titania, the electron assistance of carbon nanotube
network, and the enhancement of molybdenum. The proposed redox mechanism of the photodegradation of methylene blue on Mo-CNT/TiO2 composites is suggested. 相似文献
2.
A cobalt(II) tetra-neopentyloxy phthalocyanine-multi-walled carbon nanotubes (CoTNPPc–MWNTs) composite was synthesized and
characterized by UV–Vis spectra and transmission electron microscopy. The CoTNPPc–MWNTs glassy carbon electrode (CoTNPPc–MWNTs/GCE)
was prepared by drop coating. The electrocatalytic performance of the chemically modified electrode was investigated for oxidation
of ascorbic acid (AA). It was found that in phosphate buffer solution at pH = 6.60, the chemically modified electrode exhibited
excellent electrocatalytic activity toward the oxidation of AA. The oxidation peak current increased linearly with the concentration
of AA in the range of 10 μM–1.6 mM within the detection limit of 5 μM and low response time of 4 s. 相似文献
3.
QUANG LONG PHAM YUVARAJ HALDORAI VAN HOA NGUYEN DIRK TUMA JAE-JIN SHIM 《Bulletin of Materials Science》2011,34(1):37-43
Poly(p-phenylenediamine) (PpPD)/carboxylic acid-functionalized multiwalled carbon nanotubes (c-MWCNTs) nanocomposites were prepared by chemical oxidative polymerization using potassium persulfate (K2S2O8) as an oxidant. Field-emission scanning electron microscopy (FE–SEM) and field-emission transmission electron microscopy
(FE–TEM) showed that a tubular layer of PpPD was coated on the surface of carbon nanotubes with a thickness of 10–20 nm. FT–IR analysis provided an evidence for the
formation of nanocomposites. The thermal stability of nanocomposites was improved by addition of c-MWCNTs as confirmed by thermogravimetric analysis (TGA). XRD spectra showed that the crystalline nature of PpPD was not affected much by the addition of c-MWCNTs. As the content of c-MWCNTs was increased, the electrical conductivity of the nanocomposites increased due to the interaction between polymer
and nanotubes that enhances electron delocalization. 相似文献
4.
Hua-Qiang Wu Pin-Shi Yuan Hong-Yan Xu Dong-Mei Xu Bao-You Geng Xian-Wen Wei 《Journal of Materials Science》2006,41(20):6889-6894
Fe–Co alloy nanoparticles with different size were attached on the carbon nanotubes through adjusting the ratio of the metal
to carbon in the mixed solution of nitrate with Fe:Co = 1:1 (molar ratio) via wet chemistry. X-ray powder diffraction (XRD),
transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray
spectrometry (EDX) indicated that the Fe–Co alloy nanoparticles attached on the surface of carbon nanotubes has body-centered
cubic (bcc) structure, with sizes in the range of 13–25 nm and in the shape of spheroids. Magnetization measurements indicated
that both the coercivities and the saturation magnetizations altered with size changes of the Fe–Co alloy nanoparticles. The
saturation magnetization decreases with decreasing the Fe–Co alloy nanoparticles’ sizes. A decrease in coercivity with increasing
Fe–Co size together with a local maximum coercivity at size of ca. 15 nm is visible. A linear relationship between the inverse particle diameter and the coercivity was found for larger particles.
These demonstrated that the chemical method here is promising for fabricating Fe–Co alloy nanoparticles coated on carbon nanotubes
for magnetic storage applications. 相似文献
5.
O. Yu. Ivanshina M. E. Tamm E. V. Gerasimova A. P. Sirotina S. V. Savilov L. V. Yashina 《Inorganic Materials》2011,47(8):858-863
Using conical multiwalled carbon nanotubes (CNTs), we have prepared Pt/CNT and Pt/TiO2/CNT nanocomposites with an average platinum particle size of 3–5 nm, Pt/Ti molar ratio on the surface in the range 3.5–4,
and C/Pt = 21–22. Titania was deposited onto the CNTs through titanium tetrachloride (TiCl4) hydrolysis. Platinum particles were produced by reducing chloroplatinic acid (H2PtCl6) with sodium borohydride (NaBH4) in the presence of CNTs. The composition and structure of the composites have been studied using X-ray photoelectron spectroscopy,
electron microscopy, X-ray diffraction, and thermogravimetry. The materials have been tested as catalysts for hydrogen oxidation
and oxygen reduction. The results demonstrate that the modification of Pt/CNT with titania enhances the catalytic activity
of the material. 相似文献
6.
Tianyou Zhai Zhanjun Gu Ying Ma Wensheng Yang Liyun Zhao Jiannian Yao 《Materials Chemistry and Physics》2006,100(2-3):281-284
Semiconductor ZnS nanotubes arrays were synthesized in the pores of the porous anodic alumina (PAA) membranes by using metal organic chemical vapor deposition (MOCVD) template methods. The morphology and structure of the ZnS nanotubes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED) and X-ray diffraction (XRD). It is found that the ZnS nanotubes with diameters in range of 140–250 nm and the length up to tens of microns are polycrystalline. Energy-dispersion spectroscopy (EDS) and X-ray photoelectron spectroscopy analysis (XPS) indicate that the stoichiometric ZnS was formed. A green-blue emission band centered at 510 nm was observed in the photoluminescence spectrum of the ZnS nanotubes. 相似文献
7.
N. M. Renukappa Siddaramaiah R. D. Sudhaker Samuel J. Sundara Rajan Joong Hee Lee 《Journal of Materials Science: Materials in Electronics》2009,20(7):648-656
A series of styrene–butadiene rubber (SBR) composites have been prepared with different weight ratios of polyacetylene based
conducting carbon black (CCB) (0–90 phr). The SBR–CCB systems are characterized for dimensional stability which is enhanced
by increasing the CCB loading because of enhancement in polymer-filler interaction. The electrical properties such as dielectric
constant (εr), dissipation factor (tan δ) and dielectric loss (ε″) of the composites have been studied. The influence of different loading
of CCB (0–90 phr), frequency of ac (100 Hz–30 MHz) and temperature (25–75 °C) on the electrical properties was studied. An
increase in dielectric constant and tan δ of the SBR composites was observed with increase in CCB content and ac frequency.
This is due to enhancement of filler–filler interaction and the increase in continuity of conducting phase. The surface morphology
has been studied using scanning electron microscopy (SEM). 相似文献
8.
Sanjaya Brahma Kalya Jagannatha Rao Srinivasarao Shivashankar 《Bulletin of Materials Science》2010,33(2):89-95
Large quantities of single-crystalline ZnO nanorods and nanotubes have been prepared by the microwave irradiation of a metalorganic
complex of zinc, in the presence of a surfactant. The method is simple, fast, and inexpensive (as it uses a domestic microwave
oven), and yields pure nanostructures of the hexagonal würtzite phase of ZnO in min, and requires no conventional templating.
The ZnO nanotubes formed have a hollow core with inner diameter varying from 140–160 nm and a wall of thickness, 40–50 nm.
The length of nanorods and nanotubes varies in the narrow range of 500–600 nm. These nanostructures have been characterized
by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area
electron diffraction (SAED). The ZnO nanorods and nanotubes are found by SAED to be single-crystalline. The growth process
of ZnO nanorods and nanotubes has been investigated by varying the surfactant concentration and microwave irradiation time.
Based on the various results obtained, a tentative and plausible mechanism for the formation of ZnO nanostructures is proposed. 相似文献
9.
Anil Kumar Mandeep Kaur Rajeev Kumar Pinaki Ranjan Sengupta Vasantha Raman Gopal Bhatia Kedar Nath Sood 《Journal of Materials Science》2010,45(5):1393-1400
Carbon–copper composites with varying copper to carbon ratio of 0.66–1.5 (by weight) were developed from coal-tar-pitch-derived
green coke (as such or modified with natural graphite) as carbon source and electrolytic grade copper powder at different
heat treatment temperatures (HTTs) of 1000–1400 °C. The physical, mechanical, and electrical properties differ depending upon
the HTT and also on copper to carbon ratio (Cu/C). The composites prepared at HTT of 1100 °C having Cu/C ratio of 0.66 and
0.9 exhibited a high bending strength of 150 and 140 MPa, bulk density of 2.63 and 2.81 gm/cm3, electrical resistivity of 1.6 and 0.96 m Ω cm and shore hardness of 88 and 84, respectively, in spite of well-known inadequate
wettability between copper and carbon. Increasing the temperature from 1100 °C for processing of the composites deteriorated
the properties mainly due to the loss of copper through melting above 1100 °C as revealed by X-ray, scanning electron microscopy,
thermal analysis and EDAX studies. 相似文献
10.
Z. M. Elimat M. S. Hamideen K. I. Schulte H. Wittich A. de la Vega M. Wichmann S. Buschhorn 《Journal of Materials Science》2010,45(19):5196-5203
The dielectric properties of epoxy/short carbon fiber composites at different concentrations 0, 5, 10 and 15% by weight, different
thicknesses 2 and 4 mm, and frequency in the range from 20 Hz to 1 MHz were characterized. Scanning electron microscopy and
differential scanning calorimetry were utilized. The alternating current (ac) electrical properties (complex impedance, dielectric
constant, dielectric loss, real part of electric modulus, imaginary part of electric modulus, electrical conductivity, and
relaxation time) were determined. It was found that the applied frequency, filler concentrations, and composite thickness
affected the ac electrical properties of the epoxy/carbon fiber composites. The dielectric behaviors of the interfacial polarization
between epoxy matrix and carbon fibers could be described by the Maxwell–Wagner–Sillars relaxation. The analysis of the complex
electric modulus in the frequency range from 20 Hz to 1 MHz revealed that the interfacial relaxation followed the Cole–Davidson
distribution of relaxation times. The universal power-law of ac conductivity was observed in the epoxy/carbon fiber composites.
The calculated power exponent (near unity) is physically acceptable within this applied model. 相似文献
11.
Ramazan Asmatulu Annamalai Karthikeyan David C. Bell Shriram Ramanathan Michael J. Aziz 《Journal of Materials Science》2009,44(17):4613-4616
Rafts of aligned, high aspect ratio TiO2 nanotubes were fabricated by an electrochemical anodization method and their axial electrical conductivities were determined
over the temperature range 225–400 °C. Length, outer diameter, and wall thickness of the nanotubes were approximately 60–80 μm,
160 nm, and 30 nm, respectively. Transmission electron microscopy studies confirmed that the TiO2 nanotubes were initially amorphous, and became polycrystalline anatase after heat treatment at temperatures as low as 250 °C
in air. The activation energy for conductivity over the temperature range 250–350 °C was found to be 0.87 eV. The conductivity
values are comparable to those of nanocrystalline and nanoporous anatase thin films reported in literature. 相似文献
12.
Carbon nanotubes (CNTs) are effective fillers/reinforcements regarding improving the properties of polymer. In the present paper, carboxylic acid functionalized CNTs were used to modify epoxy with intent to develop a nanocomposite matrix for hybrid multiscale composites combining benefits of nanoscale reinforcement with well-established fibrous composites. CNTs were dispersed in epoxy by using high energy sonication. At low contents of CNTs, hybrid multiscale composites specimens were manufactured via resin transfer molding (RTM) process. The processibility of CNTs/epoxy systems was explored with respect to their viscosity. The dispersion quality and re-agglomeration behavior of CNTs in epoxy were characterized using optical microscope. A CNTs loading of 0.025 wt% significantly improved the glass transition temperatures (Tg) of the hybrid multiscale composites. Scanning electron microscopy (SEM) was used to examine the fracture surface of the failed specimens. It is demonstrated that the addition of small amount of CNTs (0.025 wt%) to epoxy for the fabrication of multiscale carbon fabric composites via RTM route effectively improves the matrix-dominated properties of polymer based composites. Hybridization efficiency in carbon fiber reinforced composites using CNTs is found to be highly dependent on the changes in the dispersion state of CNTs in epoxy. 相似文献
13.
Carbon nanofibers prepared by a novel co-extrusion and melt-spinning of phenol formaldehyde-based core/sheath polymer blends 总被引:1,自引:0,他引:1
A novel route based on the solvent-free core/sheath melt-spinning of polypropylene/(phenol formaldehyde–polyethylene) [PP/(PF–PE)]
to prepare the carbon nanofiber (CNF) has been demonstrated in this study. The approach consists of three main steps: co-extrusion
of PP (core) and a polymer blend of PF and PE (sheath), followed by melt-spinning, to form the core/sheath fiber, stabilization
of core/sheath fiber to form the carbon fiber precursor, and carbonization of carbon fiber precursor to form the final CNF.
Both scanning electron microscopy and transmission electron microscopy images reveal long and winding CNF with diameter 100–600 nm
and length greater than 80 μm. With a yield of ~45% based on its raw material PF, the CNF exhibits regularly oriented bundles
which curl up to become rolls of wavy long fibers with clean and smooth surface. Results from X-ray diffractometry, Raman
spectroscopy, and selected area electron diffraction pattern further reveal that the CNF exhibits a mixed-phase carbon material
with graphitic particles embedded homogeneously in an amorphous carbon matrix. 相似文献
14.
Nanocomposites comprise polysilazane-derived SiCN ceramic charged with carbon nanotubes (CNTs) have been prepared by dispersion
of multi-walled CNTs with a diameter of 80 nm in a cross-linked polysilazane (HTT 1800, Clariant) using a simple roll-mixer
method. Subsequently, the composites were warm pressed and pyrolyzed in argon atmosphere. Scanning electron microscopy (SEM)
and 3D Raman imaging techniques were used as major tools to assess the dispersion of CNTs throughout the ceramic matrix. Furthermore,
studies on the effect of the volume fraction of CNTs in the nanocomposites on their electrical properties have been performed.
The specific bulk conductivities of the materials were analyzed by AC impedance spectroscopy, revealing percolation thresholds
(ρc) at CNT loadings lower than 1 vol%. Maximum conductivity amounted to 7.6 × 10−2 S/cm was observed at 5 vol% CNT. The conductivity exponent in the SiCN/CNT composites was found equal to 1.71, indicating
transport in three dimensions. 相似文献
15.
Zhang Xuezhong Huang Yudong Wang Tianyu Hu Lijiang 《Frontiers of Materials Science in China》2007,1(1):40-48
Carbon fibres (CF) were modified with different oligomeric silsesquioxane (SSO) coatings to improve the interfacial property
of carbon fibres/polyarylacetylene (CF/PAA). The interlaminar shear strength (ILSS) of CF/PAA was tested to determine the
effect of the treatment. Atomic force microscopy (AFM) in force modulation mode was adopted to study the cross-section surface
of unidirectional CF/PAA composites and the relative stiffness of various phases, including CF, interphase and resin. The
probability histogram and line distribution of CF/PAA cross-section surface relative stiffness, obtained from the statistical
analysis of relative stiffness image, were used to compare and study the interface characterizations of composites. The results
show that the ILSS increases effectively and the effects on interfacial characterizations are distinguished from each other
in accordance with the CF surface modified with different SSO coatings owing to the various structures. Cage oligomeric silsesquioxane,
including large organic groups (methacryl isobutyl-POSS), has better treatment result. AFM observations lead to the conclusion
that an interfacial transition layer with different morphology and stiffness appears in CF/PAA composites after being treated
by the SSO coatings of different structures. It can be inferred that the appearance of the transition layer may contribute
to the improvement of fibre/matrix adhesion.
Translated from Acta Materiae Compositae Sinica, 2006, 23(1): 105–111 [译自: 复合材料学报] 相似文献
16.
《Materials Letters》2007,61(8-9):1899-1903
Large-scale well-aligned carbon nanotube film and carbon nanotube bundles have been fabricated on smooth silica and rough polycrystalline ceramic substrates by pyrolysis of ferrocene/melamine mixtures. The images of transmission electron microscopy (TEM) and scanning electron microscope (SEM) show that carbon nanotubes grown on the silica substrate have uniform outer diameters of about ∼ 25 nm and lengths of about 40 μm, while those on the ceramic substrate have outer diameters from 10 to 90 nm and lengths up to 100 μm. Electron energy-loss spectroscopy (EELS) spectra show that nanotubes grown on the two different substrates are pure carbon tubes. The effects of substrate micro-morphologies on the diameters of carbon nanotubes have been discussed. 相似文献
17.
Xing-xiang Zhang Qing-jie Meng Xue-chen Wang Shi-he Bai 《Journal of Materials Science》2011,46(4):923-930
Poly(adipic acid-hexamethylene diamine) (PA66)-functionalized multi-walled carbon nanotubes (PACNT) were fabricated using
amino multi-walled carbon nanotubes (AMWNT), adipic acid-hexamethylene diamine salt as reactants at 260–270 °C. The solubility
of AMWNT in formic acid is improved after PA66 functionalization. PA66 was successfully grafted onto the surface of AMWNT
to form a core–shell nanostructure. AMWNT are surrounded by PA66 chains with an average thickness of 3 nm. The length of PA66
chains on the surface of AMWNT decreases, with the content of AMWNT increasing. The thermal decomposition temperature of the
composite is lower than that of PA66 functionalized carboxylic multi-walled carbon nanotubes. The storage modulus of PACNT
containing 5 wt% AMWNT is 2.8-fold that of PA66; and it increases as the content of AMWNT increases. 相似文献
18.
Zhi Yang Xiao-Hua Chen Shang-Zhou Xia Yu-Xing Pu Hai-Yang Xu Wen-Hua Li Long-Shan Xu Bin Yi Wei-Ying Pan 《Journal of Materials Science》2007,42(22):9447-9452
The functionalization with formaldehyde via an electrophilic substitution reaction and graft with poly (acrylic acid) (PAA)
by “grafting from” technology have been carried out for multiwalled carbon nanotubes (MWNTs) and MWNTs-PAA composites have
been formed. The IR and TEM results show presence of covalent band and so-called “core-shell” structures for MWNTs-PAA. The
MWNTs-PAA exhibits excellent suspendability in water, which is significant to explore the potential application of carbon
nanotube in biological and medical systems. 相似文献
19.
《Materials Research Bulletin》2006,41(1):92-98
EuF3 and TbF3 were successfully coated on the multi-walled carbon nanotubes (MWNTs) via the intermediate of noncovalent hydrophobic interactions of the MWNTs surface with sodium dodecyl sulfate (SDS). They were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The nanoparticle sizes of rare earth fluorides on MWNTs are less than 10 nm. The photophysical properties of the composites were investigated, which indicated the rare earth fluorides/MWNTs composites exhibited the optical transitions within the 4f shell of the rare earth ions. 相似文献
20.
Tianxiang Zhou Shanshan Mo Shuangli Zhou Wujun Zou Yingliang Liu Dingsheng Yuan 《Journal of Materials Science》2011,46(10):3337-3342
A quick and facile microwave method has been employed to prepare Mn3O4/worm-like mesoporous carbon (Mn3O4–MC) composites. Structural and morphological characterizations of worm-like mesoporous carbon and Mn3O4–MC composites have been carried out using X-ray diffraction, transmission electron microscopy, N2 adsorption–desorption, and electrochemical measurement. Cyclic voltammograms demonstrate that the Mn3O4–MC composites perform improved capacitive behavior at the range of −0.8~0.2 V (vs. Hg/HgO electrode) with reversibility.
The Mn3O4–MC composite electrode possesses an enhanced specific capacitance of 266 F g−1 at a sweep rate of 1 mV s−1. 相似文献