Can nitrones functionalize carbon nanotubes?

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2004

2019

works as a Senior Researcher in PINSTECH, Pakistan. He has received his PhD and Post-Doctorate degree in material science. His research interests include fabrication of nanomaterials and their structural, optical, magnetic, and electrical characterizations. He has authored more than 100 research articles and published 8 books. Presently, he is serving as the Editor-in-Chief of "Journal of Materials, Processing and Design" and Executive Editor of "International Journal of Nano Studies & Technology". He is also on the editorial board of several more journals in the material science field. Dr Gustavo Morari do Nascimento is a professor at the Federal University of ABC. He has vast experience in many fields related to the characterization of nanomaterials using spectroscopic techniques associated to microscopic resolution. He obtained his doctoral degree from the University of São Paulo (USP) in 2004 with a thesis about the spectroscopic characterization of nanocomposites formed by conducting polymers and clays. Afterwards, he completed a post-doctoral degree at Massachusetts Institute of Technology (MIT) in the resonance Raman study of double-walled carbon nanotubes doped with halogens under the guidance of the legendary Mildred S. Dresselhaus. Back in Brazil, he spent three years (2009-2011) at the Federal University of Minas Gerais (UFMG) working on the synthesis of nanostructured carbon modified with molecular magnets. Nowadays, his research focus is on molecular characterization of modified carbon nanostructured materials and polymer nanocomposites using different spectroscopic techniques. Resonance Raman and SERS (surface enhanced Raman spectroscopy) coupled to microscopy techniques added to X-ray absorption techniques at National Synchrotron Light Laboratory have been the main techniques employed in the investigation. Dr Marwa El-Azazy is an Analytical Chemist and "experienced educator and researcher" with 20 years of teaching experience at several institutions. Her main research interest is the construction of sensors (using microfluidic platforms for point-of-caretesting of drugs, bio-analytes, and ion-selective electrodes), chemometrics and analytical method development, spectroscopic analyses of drugs and pharmaceuticals, synthesis and characterization of nanomaterials, and development of green chemistry approaches for wastewater treatment. Dr Marwa has a track record of research inputs including >30 refereed papers in prestigious international journals, several conference presentations, two book chapters, in addition to several research grants. She serves as a reviewer for a variety of international journals.

2003

A general framework for the interpretation of infrared and Raman spectra of amorphous carbon nitrides is presented. In the first part of this paper we examine the infrared spectra. The peaks around 1350 and 1550 cm Ϫ1 found in the infrared spectrum of amorphous carbon nitride or hydrogenated and hydrogen-free amorphous carbon are shown to originate from the large dynamic charge of the more delocalized bonding which occurs in more sp 2 bonded networks. The IR absorption decreases strongly when the bonding becomes localized, as in tetrahedral amorphous carbon. Isotopic substitution is used to assign the modes to CvC skeleton modes, even those modes around 1600 cm Ϫ1 which become strongly enhanced by the presence of hydrogen. The infrared spectrum of carbon nitride may resemble the Raman spectrum at some excitation energy, but the infrared activity does not primarily result from nitrogen breaking the symmetry. In the second part we examine the Raman spectra. A general model is presented for the interpretation of the Raman spectra of amorphous carbon nitrides measured at any excitation energy. The Raman spectra can be explained in terms of an amorphous carbon based model, without need of extra peaks due to CN, NN, or NH modes. We classify amorphous carbon nitride films in four classes, according to the corresponding N-free film: a-C:N, a-C:H:N, ta-C:H:N, and ta-C:N. We analyze a wide variety of samples for the four classes and present the Raman spectra as a function of N content, sp 3 content, and band gap. In all cases, a multiwavelength Raman study allows a direct correlation of the Raman parameters with the N content, which is not generally possible for single wavelength excitation. The G peak dispersion emerges as a most informative parameter for Raman analysis. UV Raman enhances the sp 1 CN peak, which is usually too faint to be seen in visible excitation. As for N-free samples, UV Raman also enhances the CC sp 3 bonds vibrations, allowing the sp 3 content to be quantified.

The Journal of Physical Chemistry B, 2004

Single-walled nanotubes (SWNTs) industrially produced and multiwalled nanotubes (MWNTs) we produced by catalysis were investigated by transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. The observed spectral features, that is the peak position, intensity, and bandwidth, were related to some structural properties of the investigated samples. In such a way, information on the vibrational modes, nanotube diameters, and purity degree of the samples was obtained. The findings of the FTIR investigation are in perfect agreement with the TEM evidence.

The subject of this study is chemical functionalization as means of structural modification of multiwalled carbon nanotubes. The main goal of the experiments was to create highest density of carboxyl groups on multiwalled carbon nanotubes surface, necessary for further nanocomposite application. Two different types of multiwalled carbon nanotubes (I: outer diameter d = 50 ÷ 100 nm, purity ≈84%, synthesized by pyrolysis and II: outer diameter d = 10 ÷ 40 nm, purity ≈94%, synthesized by chemical vapor deposition) were treated by concentrated nitric acid (HNO3) and by alkaline mixture (NH4OH+H2O2). The alkaline medium as " milder " and less aggressive than nitric acid, was expected to be less destructive and cause minimal structural damage on multiwalled carbon nanotubes surface. Structural changes due to oxidation were observed by the Raman analysis, while the ratio of the intensities of the D and G peak was used to estimate the concentration of defects. Pristine and functionalized multiwalled carbon nanotubes were characterized by thermogravimetric analysis, scanning electron microscopy, ultraviolet–visible spectroscopy and zeta (ζ) spectroscopy. The results showed that functionalization initiates changes in carbon nanotubes structure as well as in their density of states. It also results in carbon nanotubes shortening and exfoliation and decreases their agglomeration tendency. Carbon nanotubes functionalized by both acid and alkaline treatment can successfully replace conventional carbon fibers as fillers in polymer composites for sensing application.

Journal of Nanoelectronics and Optoelectronics, 2012

Crystalline structure perfection of carbonaceous nanomaterial (CNM) "Taunit" which constitutes the multi-walled nanotubes was studied using a Raman spectroscopy technique. CNM "Taunit" was synthesized by MOCVD method. The pristine material, the samples annealed at different temperatures and the samples functionalized by Pt-catalyst nanoparticles were investigated. It has been found that "Taunit" belongs to the poorly organized carbon materials but its crystalline structure was observed to order while the annealing temperature increased. D1 and G Raman band (at 1350 and 1580 cm −1 , respectively) intensity ratios were calculated to estimate the crystal structure ordering of CNM "Taunit". The investigation of the influence of functionalization by the catalyst nanoparticles shows that Pt-catalyst precipitation on the surface of MWNTs leads to the increase of the defect band intensity due to an appearance of lattice defects.

physica status solidi (b), 2008

Diamond and Related Materials, 2004

A comparison between neutron scattering data and computational results, derived from a Hartree simulation, for fullerene is reported. In order to apply the same computational approach for carbon nanotubes produced by catalysis, the structural properties of these samples have been investigated by means of transmission electron microscopy and Fourier-transform infrared spectroscopy. The obtained findings furnish information on the tube diameters and on the purity degree of the samples. ᮊ

Physica B: Condensed Matter, 2002

The use of Raman spectroscopy to elucidate the vibrational and electronic structure of single wall carbon nanotubes is reviewed. The special role played by single nanotube spectroscopy in the ðn; mÞ structural characterization of individual nanotubes and in the elucidation of the spectra of nanotube bundles is emphasized. r