Cu (I) phenyl acetylide was used as a source of copper to achieve a homogeneous distribution of Cu2O nanocrystals (10–80 nm) decorated on multiwalled carbon nanotubes (MWCNTs) having an average diameter of 10 nm. Pristine
MWCNTs were first oxygen-functionalized by treating them with a mixture of concentrated (H2SO4/HNO3 : 3/1) acids and the products were characterized by X-ray powder diffraction, transmission and scanning electron microscopy,
energy dispersive X-ray analysis, X-ray photoelectron spectroscopy and thermogravimetric analysis. An easy, efficient and
one-step impregnation method was followed to produce copper-containing nanoparticles on the MWCNTs. The copper-treated MWCNTs
dried at room temperature were seen to be well decorated by copper-containing nanoparticles on their outer surface. The MWCNTs
were then heat-treated at 400 °C in a nitrogen atmosphere to produce a homogeneous distribution of cuprous oxide nanocrystals
on their surface. By varying the ratio of copper to oxygen-functionalized MWCNTs, Cu2O nanocrystals decorated on MWCNTs with different copper content can be obtained. 相似文献
The specific features of changes in the electronic structure of multi-walled carbon nanotubes (MWCNTs) due to the interaction with an amorphous tin oxide in the SnOx/MWCNT composite formed by magnetron sputtering have been investigated using X-ray spectroscopy. It has been shown that the formation of chemical bonds responsible for significant changes in the local and electronic structures of the outer layers of MWCNTs occurs at the boundaries of the “amorphous oxide/MWCNT” contacts. The vacuum annealing of the composite leads to the disturbance of the chemical interaction at interfaces of the composite and to a partial recovery of the local structure of the outer layers of MWCNTs. A decrease in the amount of oxygen in the tin oxide under vacuum annealing conditions causes an increase in the number of unpaired Sn 5s electrons, which, in turn, enhances the charge transfer through the interfaces in the composite and leads to a splitting of the π*-subsystem of the outer layers of MWCNTs. 相似文献
Ionics - In this study, the preparation of a glassy carbon electrode (GCE) modified with multiwall carbon nanotubes|MnO2 nanoparticles (MWNT|MnO2) was developed for electrocatalytic detection of... 相似文献
We report an experimental and a theoretical study of the radial elasticity of multiwalled carbon nanotubes as a function of external radius. We use atomic force microscopy and apply small indentation amplitudes in order to stay in the linear elasticity regime. The number of layers for a given tube radius is inferred from transmission electron microscopy, revealing constant ratios of external to internal radii. This enables a comparison with molecular dynamics results, which also shed some light onto the applicability of Hertz theory in this context. Using this theory, we find a radial Young modulus strongly decreasing with increasing radius and reaching an asymptotic value of 30+/-10 GPa. 相似文献
Growth of individual, vertically aligned multiwalled carbon nanotubes (VACNT) on patterned Si wafers using dc plasma-enhanced CVD is described. The selective growth of individual VACNT within larger holes etched in Si is demonstrated for the first time. 相似文献
The effect hydrostatic pressure of up to 9 GPa has on the electrical behavior of polymer composites based on multiwalled carbon nanotubes (MWCNT) is investigated at room temperature. The ratio R9GPa/R0 ≈ 7 for samples with resistance in the kilo-ohm range is higher than for samples in the ohm range. Pressure-induced MWCNT features at P ≈ 1.5 GPa are associated with the deformation of the circular form of nanotube walls, in agreement with theoretical predictions. Measurements of direct and reverse resistance and current voltage characteristics under pressure demonstrate the reversibility of electrophysical properties, which could find practical application in creating pressure sensors. 相似文献
Nanostructures formed in a titanium dioxide (TiO2)–poly(styrene)‐block‐poly(ethyleneoxide) nanocomposite film on top of fluor‐doped tin oxide (FTO) layers are investigated. The combinatorial approach is based on probing a wedge‐shaped FTO‐gradient with grazing incidence small angle X‐ray scattering (GISAXS) in combination with a moderate micro‐focus X‐ray beam. The characteristic lateral length is given by adjacent nanowire‐shaped TiO2 regions. It decreases from 200 nm on the thick FTO layer to 90 nm on the bare glass surface.
We characterize through large-scale simulations the nonlinear elastic response of multiwalled carbon nanotubes (MWCNTs) in torsion and bending. We identify a unified law consisting of two distinct power law regimes in the energy-deformation relation. This law encapsulates the complex mechanics of rippling and is described in terms of elastic constants, a critical length scale, and an anharmonic energy-deformation exponent. The mechanical response of MWCNTs is found to be strongly size dependent, in that the critical strain beyond which they behave nonlinearly scales as the inverse of their diameter. These predictions are consistent with available experimental observations. 相似文献
We report on the characterization of torsional oscillators which use multiwalled carbon nanotubes as the spring elements. Through atomic-force-microscope force-distance measurements we are able to apply torsional strains to the nanotubes and measure their torsional spring constants, and estimate their effective shear moduli. The data show that the nanotubes are stiffened by repeated flexing. We speculate that changes in the intershell mechanical coupling are responsible for the stiffening. 相似文献
We report that a twisting deformation mode emerges with the rippling in bent multiwalled carbon nanotubes via atomistic simulations. This mode arises from the curvature-induced lattice mismatch, and is energetically favorable. For the nanotubes with larger radii, twisting may enhance the local strain relaxation. Under the thermal fluctuation, the nucleation of defects involves bond breaking and reconstruction due to strain localization. The defective inner tubes undergo the cyclic torsion, resulting in unstable necking and even failure. Prior to fracture, a monatomic chain is formed under the combination of bending and twisting. 相似文献
Polarized Raman spectra of high purity aligned arrays of multiwalled carbon nanotubes, prepared on silica substrates from the thermal decomposition of a ferrocene-xylene mixture, show a strong dependence of the graphitelike G band and the disorder-induced D band on the polarization geometry employed in the experiments. The experimental G-band intensity exhibits a minimum at straight theta(m) = 55 degrees in the VV configuration, in good agreement with theoretical predictions of a characteristic minimum at 54.7 degrees for A(1g) modes in single wall nanotubes, where straight theta(m) denotes the angle between the polarization direction and the nanotube axis. 相似文献
We investigate the limits of high energy transport in multiwalled carbon nanotubes (MWNTs). In contrast to metal wires, MWNTs do not fail in the continuous, accelerating manner typical of electromigration. Instead, they fail via a series of sharp, equally sized current steps. We assign these steps to the sequential destruction of individual nanotube shells, consistent with the MWNT's concentric-shell geometry. Furthermore, the initiation of this failure is very sensitive to air exposure. In air failure is initiated by oxidation at a particular power, whereas in vacuum MWNTs can withstand much higher power densities and reach their full current carrying capacities. 相似文献
Carbon-based systems have been discussed as prospective alternatives for conventional metal-based catalysts over the past decade. These studies were motivated by the abundance, low cost, lightweight and diversity of structural allotropes of carbon. We reported here the synthesis of a new type of unzipped multiwalled carbon nanotubes/titanium dioxide (UzMWCNT/TiO2) nanocomposite by the two-stage procedure. By the modified Hummers method, multiwalled carbon nanotubes (MWCNTs) were converted to oxidized multi-walled carbon nanotubes (O-MWCNT). Then, through a facile ultrasound-assisted route prepared UzMWCNT/TiO2 nanocomposite. For this, the oxidized multiwalled carbon nanotubes are treated with TiCl4 under an ultrasonic probe for 3 h to generate UzMWCNT/TiO2 and then explored its environmental friendliness and energy applications as a supercapacitor. This novel UzMWCNT/TiO2 nanocomposite was characterized using XRD, TGA, FT-IR, Raman, TEM and EDX analysis. The electrochemical performance can be evaluated by using cyclic voltammetry (CV) and galvanostatic charging-discharging (GCD) study. Finally, the electrodes prepared using UzMWCNT/TiO2 nanocomposite have been analyzed through electrochemical impedance spectroscopy (EIS) to probe the charge transfer characteristics and the results are consistent with other electrochemical measurements. 相似文献