Search results for "Carbon nanotubes"
showing 10 items of 165 documents
Catechol-Functionalized Carbon Nanotubes as Support for Pd Nanoparticles
2022
Carbon nanotubes have been covalently functionalized with catechol moieties through the formation of the corresponding aryl radicals obtained by reacting 4-aminocatechol with isoamyl nitrite. The functionalized multiwalled carbon nanotubes have been in turn used to immobilize Pd(II) ions on its surface forming catechol-Pd complexes, which were reduced to Pd nanoparticles (NPs). The so-obtained hybrid material has been characterized by means of thermogravimetric analysis coupled with differential scanning calorimetry (TGA-DSC), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). This latter technique allowed to estimate the nanoparticle size (5.7 +/- 2.8 nm) wh…
Heterogenizing palladium tetraiodide catalyst for carbonylation reactions
2022
We report the first example of successful heterogenization of the classical PdI42- carbonylation catalyst, achieved in two simple steps from ionic liquid-functionalized multi-walled carbon nanotubes (MWCNTs). The newly developed materials (PdI4@MWCNT-imi-X, X = Br, I) present the PdI42- anion supported on an imidazolium network (imi) grown on MWCNTs and have been fully characterized. The activity of PdI4@MWCNT-imi-X has been successfully tested in a paradigmatic carbonylation reaction, the oxidative monoaminocarbonylation of 1-alkynes with amines to give high value added 2-ynamides (obtained in good yields, 50–84%, starting from various substrates). The heterogeneous catalyst could be easil…
Hybrid ionogels as potential antioxidant agents
In the present study, the influence of CNTs on the gelling ability of some carboxylate imidazolium gelators in ionic liquid solutions has been investigated.
Hydrogen Bonding Donor–Acceptor Carbon Nanostructure
2012
The natural process of photosynthesis is paradigmatic in converting sunlight into energy. This complicated process requires a cascade of energy- and electron-transfer events in a highly organised matrix of electron–donor, electron–acceptor and antennae units and has prompted researchers to emulate it. In fact, energy- and electron-transfer processes play a pivotal role in molecular-scale optoelectronics. In this chapter we compile a number of remarkable examples of noncovalent aggregates formed by the combination of carbon-based electroactive species (fullerenes and carbon nanotubes) hydrogen bonded with a variety of moieties. We will show that: (a) the connection of complementary electroac…
Glucose-triggered release using enzyme-gated mesoporous silica nanoparticles.
2013
[EN] A new gated nanodevice design able to control cargo delivery using glucose as a trigger and cyclodextrin-modified glucose oxidase as a capping agent is reported.
Measurements of tunneling conduction to carbon nanotubes and its sensitivity to oxygen gas
2012
We have measured the conductive properties of junctions between carbon nanotubes (CNT) and non-noble metals $M$ ($M$ = Al, Ti, Nb), which are separated by the native oxide (${M}_{\mathit{OX}}$) of the metal. Reproducible and asymmetric current-voltage characteristics were obtained from Ti/Ti${}_{\mathit{OX}}$/CNT and Nb/Nb${}_{\mathit{OX}}$/CNT junctions, while Al/Al${}_{\mathit{OX}}$/CNT exhibited no current until breakdown, which is attributed to the larger bandgap of Al${}_{\mathit{OX}}$. The conduction in the Ti- and Nb-based junctions is not due to direct tunneling since they exhibit strong temperature dependence. The presence of oxygen is shown to drastically, but reversibly, modify t…
Resistance simulations for junctions of SW and MW carbon nanotubes with various metal substrates
2011
Abstract This theoretical study focuses on junctions between the carbon nanotubes (CNTs) and contacting metallic elements of a nanocircuit. Numerical simulations on the conductance and resistance of these contacts have been performed using the multiple scattering theory and the effective media cluster approach. Two models for CNT-metal contacts have been considered in this paper: a) first principles “liquid metal” model and b) semi-empirical model of “effective bonds” based on Landauer notions on ballistic conductivity. Within the latter, which is a more adequate description of chirality effects, we have simulated both single-wall (SW) and multi-wall (MW) CNTs with different morphology. Res…
Thiophene pyrenyl derivatives for the supramolecular processability of single-walled carbon nanotubes in thin film heterojunction
2017
Abstract A major problem for the use of single-wall carbon nanotubes (SWCNTs) in electronic devices relates to their poor processability. Chemical modification inevitably introduces defects in the nanotube lattice, resulting in a loss of electronic properties. In this contest, we report on a supramolecular approach with the aim of increasing the dispersion of SWCNTs in solution and in organic semiconductor matrices by ensuring the optoelectronic properties. In particular, new pyrenyl derivatives of thiophene have been synthesized and used to improve the solubility of SWCNTs for electron transfer in thin film heterojunction with poly(3-hexylthiophene) (P3HT) as donor system. Photoinduced ele…
A stochastic shape and orientation model for fibres with an application to carbon nanotubes
2012
Methods are introduced for analysing the shape and orientation of planar fibres from greyscale images of fibrous systems. The sequence of image processing techniques needed for segmentation of fibres is described. The identified fibres were interpreted as deformed line segments for which two shape and two orientation parameters are estimated by the maximum likelihood method. The methods introduced are shown to perform quite well for simulated systems of deformed line segments with known properties. They were applied to TEM images of carbon nanotubes embedded in polycarbonate.
Study of the role of particle-particle dipole interaction in dielectrophoretic devices for biomarkers identification
2015
A three dimensional Coupled Monte Carlo-Poisson method has been used to evaluate the impact of particle-particle dipole interactions in the equilibrium distribution of a system of uncharged polarizable particles suspended in a static liquid medium under the action of an oscillating non-uniform electric field generated by polynomial electrodes. We compare the simulated distributions with experimental ones both for micro- (MDA-MB-231 breast tumor cells) and nano-(multiwall carbon nanotubes) particles. In both cases the equilibrium distributions near the electrodes are dominated by dipole interactions which locally enhance the DEP effect and promote long particles chains.