Photoconductivity Study of Modified Carbon Nanotube/Oxotitanium Phthalocyanine Composites

The effects of central metals on ammonia sensing of metallophthalocyanines covalently bonded to graphene oxide hybrids

Stably dispersed aPcM–GO hybrids were prepared by a facile amidation reaction with excellent NH₃ sensing properties at room temperature, which rely to the aPcM functionalization on GO.

Nonlinear optical behavior of porphyrin functionalized nanodiamonds: an efficient material for optical power limiting

The nonlinear optical mechanisms and the optical limiting behavior of porphyrin functionalized detonation nanodiamonds are investigated and compared to the conventional detonation nanodiamonds (DNDs). The optical limiting behavior is characterized by means of nonlinear transmittance, Z-scan, and scattered intensity measurements when submitted to a nanosecond pulsed Nd:YAG laser operating at the second harmonic wavelength. We found that the largest nonlinear attenuation was observed on the 4,4^',4^'',4^'''-(porphyrin-5, 10, 15, 20-tetrayl) tetrakis benzoic acid (PCOOH) suspension. Using Z-scan experiments, it is shown that nonlinear refraction predominates in the unfunctionalized DND suspension, while nonlinear absorption is the most relevant mechanism in the porphyrin functionalized DNDs. Furthermore, a stronger backscattered intensity signal is highlighted for the unfunctionalized DNDs through nonlinear scattering measurements.

Enhanced performance in capacitive force sensors using carbon nanotube/polydimethylsiloxane nanocomposites with high dielectric properties

Force sensors have attracted tremendous attention owing to their applications in various fields such as touch screens, robots, smart scales, and wearable devices. The force sensors reported so far have been mainly focused on high sensitivity based on delicate microstructured materials, resulting in low reproducibility and high fabrication cost that are limitations for wide applications. As an alternative, we demonstrate a novel capacitive-type force sensor with enhanced performance owing to the increased dielectric properties of elastomers and simple sensor structure. We rationally design dielectric elastomers based on alkylamine modified-multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS) composites, which have a higher dielectric constant than pure PDMS. The alkylamine-MWCNTs show excellent dispersion in a PDMS matrix, thus leading to enhanced and reliable dielectric properties of the composites. A force sensor array fabricated with alkylamine-MWCNT/PDMS composites presents an enhanced response due to the higher dielectric constant of the composites than that of pure PDMS. This study is the first to report enhanced performance of capacitive force sensors by modulating the dielectric properties of elastomers. We believe that the disclosed strategy to improve the sensor performance by increasing the dielectric properties of elastomers has great potential in the development of capacitive force sensor arrays that respond to various input forces.

Rigid thermosetting epoxy/multi-walled carbon nanotube foams with enhanced conductivity originated from a flow-induced concentration effect

Rigid epoxy/MWCNT foams were innovatively prepared using expandable microspheres, a flow-induced concentration effect increases the inter-connectivity caused by the thermally triggered expansion of microspheres, improving the electric conductivity.

Progress towards high-power Li/CFx batteries: electrode architectures using carbon nanotubes with CFx

This perspective describes the current status of lithium–carbon monofluoride batteries and highlights the opportunities for the development of high-power Li/CF_x batteries via utilization of carbon nanotubes.

Axially phenoxylated aluminum phthalocyanines and their application in organic photovoltaic cells

Phenoxylation of chloro aluminum phthalocyanine (Cl-AlPc) can be easily achieved only when using “acidic phenols”. Once incorporated into unoptimized organic photovoltaics (OPVs) the result is an increase in the V_OC.

Application of Carbon Nanotubes in Nanomedicine

Carbon Nanotubes (CNTs) have become a technological field with great potential since they can be applied in almost every aspect of modern life. One of the sectors where CNTs are expected to play a vital role is the field of medical science. This chapter focuses on the latest developments in applications of CNTs for nanomedicine. A brief history of CNTs and a general introduction to the field are presented. Then, the preparation of CNTs that makes them ideal for use in medical applications is highlighted. Examples of common applications, including cell penetration, drug delivery, and gene delivery and imaging are given. Finally, the toxicity of carbon nanotubes is discussed.

Plasma-assisted interface engineering of boron nitride nanostructure films

Today many aspects of science and technology are progressing into the nanoscale realm where surfaces and interfaces are intrinsically important in determining properties and performances of materials and devices. One familiar phenomenon in which interfacial interactions play a major role is the wetting of solids. In this work we use a facile one-step plasma method to control the wettability of boron nitride (BN) nanostructure films via covalent chemical functionalization, while their surface morphology remains intact. By tailoring the concentration of grafted hydroxyl groups, superhydrophilic, hydrophilic, and hydrophobic patterns are created on the initially superhydrophobic BN nanosheet and nanotube films. Moreover, by introducing a gradient of the functional groups, directional liquid spreading toward increasing [OH] content is achieved on the films. The resulting insights are meant to illustrate great potentials of this method to tailor wettability of ceramic films, control liquid flow patterns for engineering applications such as microfluidics and biosensing, and improve the interfacial contact and adhesion in nanocomposite materials.

Revealing the ameliorating effect of chromium oxide on a carbon nanotube catalyst in propane oxidative dehydrogenation

Schematic view of PODH reaction on CrOx doped CNT.

Synthesis and Structural Characterization of Surface-Modified TiO2

oleic acid-modified nano-titanium dioxide were synthesized by Oleic acid and tetrabutyl titanate via the sol-gel method, and characterized by IR TEM TG-DT A and XPS. Comparison with the data of the IR, the combination of carboxyl is chelating with Ti atoms. Based on the analysis of IR, TG-DTA and XPS, this paper suggests a model about the oleic acid-modified titanium dioxide nano-structure, and to provide a basis for future applications.

Quantum dot modified multiwall carbon nanotubes

A novel strategy for the fabrication of multiwall carbon nanotube-nanocrystal heterostructures is shown. Different quantum dots (QDs) with narrow size distributions were covalently coupled to carbon nanotubes (CNTs) and silica-coated CNTs in a simple, uniform, and controllable manner. The structural and optical properties of CNT/QD heterostructures are characterized by electron microscopy and photoluminescence spectroscopy. Complete quenching of the PL bands in both QD core and core/shell heterostructures was observed after adsorption to the CNTs, presumably through either carrier ionization or energy transfer. The deposition of a silica shell around the CNTs preserves the fluorescence properties by insulating the QD from the surface of the CNT.

Single-Wall Carbon Nanotubes Bearing Covalently Linked Phthalocyanines − Photoinduced Electron Transfer

HiPco single-walled carbon nanotubes (SWNTs) have been sidewall-functionalized with phthalocyanine addends following two different approaches: a straightforward Prato reaction with N-octylglycine and a formyl-containing phthalocyanine, and a stepwise approach that involves a former Prato cycloaddition to the double bonds of SWNTs using p-formyl benzoic acid followed by esterification of the derivatized nanotubes with an appropriate phthalocyanine molecule. The two materials obtained by these routes comprise different carbon/Pc-addenda ratios, as evidenced by Raman, TGA, and photophysical studies. The occurrence of electron transfer from photoexcited phthalocyanines to the nanotube framework in these ZnPc-SWNT ensembles is observed in transient absorption experiments, which confirm the absorption of the one-electron oxidized ZnPc cation and the concomitant bleaching of the van Hove singularities typical from SWNTs. Charge-separation (i.e., 2.0 x 1010 s(-1)) and charge-recombination (i.e., 1.5 x 106 s(-1)) dynamics reveal a notable stabilization of the radical ion pair product in dimethylformamide.

Hybridization of thiol-functionalized poly(phenylacetylene) with cadmium sulfide nanorods: improved miscibility and enhanced photoconductivity

Molecules of a thiol-functionalized phenylacetylene derivative were assembled on the CdS nanorod surface and copolymerized with phenylacetylene, affording an inorganic semiconductor-conjugated polymer hybrid with excellent solubility and high photoconductivity.

Synthesis, Photochemistry, and Electrochemistry of Single-Wall Carbon Nanotubes with Pendent Pyridyl Groups and of Their Metal Complexes with Zinc Porphyrin. Comparison with Pyridyl-Bearing Fullerenes

A soluble, functionalized Py-SWNT has been synthesized and characterized by solution (1)H and (13)C NMR, FT-Raman, and electron microscopy. Experimental data indicate that Py-SWNT has short tubes with pentyl esters at the tips and pyridyl isoxazolino units along the walls. The synthesis of Py-SWNT is based on a 1,3-dipolar cycloaddition of a nitrile oxide on the SWNT walls, similar to 1,3-dipolar cycloadditions that are common for fullerene functionalization. The resulting Py-SWNT forms a complex with a zinc porphyrin (ZnPor) in a way similar to that reported for pyridyl-functionalized [60]-fullerenes. Formation of this metal-ligand complex was firmly established by a detailed electrochemical study. However, in contrast to the behavior observed for the ZnPor/Py-C(60) complex, photochemical excitation of the complex between ZnPor/Py-SWNT does not lead to electron transfer with the generation of charge-separated states. Fluorescence and laser flash studies indicate that the main process is energy transfer from the singlet ZnPor excited state to the Py-SWNT with observation of emission from Py-SWNT. Triplet ZnPor excited-state quenching by Py-SWNT is only observed in polar solvents such as DMF, but not in benzonitrile.

Interaction of Porphine and Its Metal Complexes with C60 Fullerene: A DFT Study

We performed DFT calculations (BLYP general-gradient approximation in conjunction with a double numerical basis set) for the interaction of free porphine ligand and a number of its metal complexes with C60 molecule to analyze how the nature of a central metal ion influences the geometry and electronic characteristics (electrostatic potential and spin density distribution and highest-occupied molecular orbital (HOMO) and lowest-unoccupied molecular orbital (LUMO) structure). We found that the presence of a central metal ion is crucial for a strong interaction. The energy of interaction between H2P and C60 is -0.3 kcal mol(-1) only, whereas the formation energies for the metal complexes vary from -27.3 kcal mol(-1) for MnClP.C60 to -45.8 kcal mol(-1) for MnP.C60. As a rule, the formation energy correlates with the separations between porphinate and fullerene molecules; the Mn and Fe complexes exhibit the closest approach of ca. 2.2 A between the metal ion and carbon atoms of C60. In most porphine-C60 complexes studied, the two closest contacts of central metal ion or H are those with carbon atoms of the (6,6) bond; VOP.C60 is the only exception, where the closest V...C contacts involve the (5,6) bond. The macrocycle geometry changes, and the magnitude of the effect depends on the central atom, being especially dramatic for Mn, MnCl, and Fe complexes. The shape of LUMOs in most complexes with C60 is not affected notably as compared to the LUMO of the isolated C60 molecule. In the case of Fe, the HOMO extends from the central atom to two opposite pyrrol rings. At the same time, the HOMO-LUMO gap energy decreases drastically in most cases, by ca. 20-30 kcal mol(-1). For electrostatic potential distribution, we systematically observed that the negative lobe contacting C60 shrinks, whereas the opposite one becomes notably bigger. In the case of paramagnetic complexes of VO, Mn, FeCl, Co, and Cu, spin density distribution was analyzed as well.

Fabrication and Photoconductivity Study of Copper Phthalocyanine/Perylene Composite with Bulk Heterojunctions Obtained by Solution Blending

Copper tetra-(octyl-alkoxy-carbonyl)-phthalocyanine (CuPc-C8) and 3,4,9,10-tetra-(octyl-alkoxy-carbonyl)-perylene (Pery-C8) attached with long alkyl chains by covalent bonds were synthesized. Both of the two compounds showed good solubility in organic solvents, and the compatibility between them was improved. The novel composite of CuPc-C8/Pery-C8 was prepared by the solution-blending method. Atomic force microscopy (AFM) demonstrated the formation of the bulk heterojunction structure in their cast-coated films. Enhanced photosensitivity was observed in the photoreceptor made from the CuPc-C8/Pery-C8 composite, which was interpreted in terms of the large interfacial area between the two components due to the existence of the bulk heterojunction structure.