Chemistry of Carbon Nanotubes

Rakov, E. G.

doi:10.1201/9781420004014.ch5

Cited by 10 publications

(10 citation statements)

References 693 publications

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“…Great interest in these materials has been stimulated by a wide variety of their applications in photocatalysis, heterogeneous catalysis, gas sensors, and electrochemical capacitors. The modification of the MWCNTs' outer surface with various metal-containing nanoparticles [5,6] expands the nanotubes functional properties range [7], giving them the necessary magnetic [8], catalytic [9] and electronic [10] properties. A hybrid material based on MWCNTs with a surface decorated by copper nanoparticles (Cu/MWCNTs nanocomposite), was successfully used as a catalyst for the reduction of germanium tetrachloride by hydrogen [11].…”

Section: Introductionmentioning

confidence: 99%

“…Regarding MWCNTs, such modification can be implemented by the deposition of continuous 1-50 nm thick metal containing coatings onto the MWCNTs' outer surface by the metal organic chemical vapor deposition (MOCVD) method. In our previous paper [19] was reported about the possibility of pyrolytic tungsten deposition on the MWCNT surface by the MOCVD method with tungsten hexacarbonyl W(CO) 6 used as a precursor. It was shown that the tungsten pyrolytic coating on the MWCNT surface is the finely dispersed phase of tungsten carbide WC (1−x) .…”

Section: Introductionmentioning

confidence: 99%

“…Vertical lines show the Ti2p, O1s, and N1s absorption edges in the first and second orders of reflection from the diffraction grating; dashed horizontal line is the level of the scattered long-wave background; (b) spectral dependences of the measured TEY signal (2), monochromatized TEY signal (4) and second-order radiation (5) on the pure gold surface using 150 nm Ti filter. The arrows indicate the absorption edges in the first and second diffraction orders; (c) spectral dependences of the TEY monochromatic signal on the Au plate with a 150 nm Ti filter (4), I0E0j(E0)(6) and the absorption cross section of the gold atom[23] (dashed line) in Mb (right scale).…”

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confidence: 99%

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The Structure and Chemical Composition of the Cr and Fe Pyrolytic Coatings on the MWCNTs’ Surface According to NEXAFS and XPS Spectroscopy

et al. 2020

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The paper is devoted to the structure and properties of the composite material based on multi-walled carbon nanotubes (MWCNTs) covered with pyrolytic iron and chromium. Fe/MWCNTs and Cr/MWCNTs nanocomposites have been prepared by the metal organic chemical vapor deposition (MOCVD) growth technique using iron pentacarbonyl and bis(arene)chromium compounds, respectively. Composites structures and morphologies preliminary study were performed using X-ray diffraction, scanning and transmission electron microscopy and Raman scattering. The atomic and chemical composition of the MWCNTs’ surface, Fe-coating and Cr-coating and interface—(MWCNTs surface)/(metal coating) were studied by total electron yield method in the region of near-edge X-ray absorption fine structure (NEXAFS) C1s, Fe2p and Cr2p absorption edges using synchrotron radiation of the Russian-German dipole beamline (RGBL) at BESSY-II and the X-ray photoelectron spectroscopy (XPS) method using the ESCALAB 250 Xi spectrometer and charge compensation system. The absorption cross sections in the NEXAFS C1s edge of the nanocomposites and MWCNTs were measured using the developed approach of suppressing and estimating the contributions of the non-monochromatic background and multiple reflection orders radiation from the diffraction grating. The efficiency of the method was demonstrated by the example of the Cr/MWCNT nanocomposite, since its Cr2p NEXAFS spectra contain additional C1s NEXAFS in the second diffraction order. The study has shown that the MWCNTs’ top layers in composite have no significant destruction; the MWCNTs’ metal coatings are continuous and consist of Fe3O4 and Cr2O3. It is shown that the interface between the MWCNTs and pyrolytic Fe and Cr coatings has a multilayer structure: a layer in which carbon atoms along with epoxy –C–O–C– bonds form bonds with oxygen and metal atoms from the coating layer is formed on the outer surface of the MWCNT, a monolayer of metal carbide above it and an oxide layer on top. The iron oxide and chromium oxide adhesion is provided by single, double and epoxy chemical binding formation between carbon atoms of the MWCNT top layer and the oxygen atoms of the coating, as well as the formation of bonds with metal atoms.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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The Structure and Chemical Composition of the Cr and Fe Pyrolytic Coatings on the MWCNTs’ Surface According to NEXAFS and XPS Spectroscopy

et al. 2020

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“…Hybrid materials based on MWCNTs are the subject of intensive investigations [17] because of a large choice of the methods of their synthesis (electrochemical techniques, various deposition methods such as atomic layer deposition, pulsed laser deposition, physical and chemical vapor deposition, etc.). The MWCNT wall's modification with various metal-containing nanoparticles [18,19] can expand the range of the nanotubes' functional properties [20], giving them the required magnetic [21], catalytic [22] and electronic [23] properties. The Cu 2 O/Cu/MWCNT nanocomposite has successfully proved to be a catalyst for the germanium tetrachloride reduction with hydrogen [24,25].…”

Section: Introductionmentioning

confidence: 99%

Studies of Buried Layers and Interfaces of Tungsten Carbide Coatings on the MWCNT Surface by XPS and NEXAFS Spectroscopy

et al. 2020

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Currently, X-ray photoelectron spectroscopy (XPS) is widely used to characterize the nanostructured material surface. The ability to determine the atom distribution and chemical state with depth without the sample destruction is important for studying the internal structure of the coating layer several nanometers thick, and makes XPS the preferable tool for the non-destructive testing of nanostructured systems. In this work, ultra-soft X-ray spectroscopy methods are used to study hidden layers and interfaces of pyrolytic tungsten carbide nanoscale coatings on the multi-walled carbon nanotube (MWCNT) surfaces. XPS measurements were performed using laboratory spectrometers with sample charge compensation, and Near Edge X-ray Absorption Fine Structure (NEXAFS) studies using the Russian–German dipole beamline (RGBL) synchrotron radiation at BESSY-II. The studied samples were tested by scanning and transmission electron microscopy, X-ray diffractometry, Raman scattering and NEXAFS spectroscopy. It was shown that the interface between MWCNT and the pyrolytic coating of tungsten carbide has a three-layer structure: (i) an interface layer consisting of the outer graphene layer carbon atoms, forming bonds with oxygen atoms from the oxides adsorbed on the MWCNT surface, and tungsten atoms from the coating layer; (ii) a non-stoichiometric tungsten carbide WC1-x nanoscale particles layer; (iii) a 3.3 nm thick non-stoichiometric tungsten oxide WO3-x layer on the WC1-x/MWCNT nanocomposite outer surface, formed in air. The tungsten carbide nanosized particle’s adhesion to the nanotube outer surface is ensured by the formation of a chemical bond between the carbon atoms from the MWCNT upper layer and the tungsten atoms from the coating layer.

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“…This process involves harsh treatment with heat or strong acids (nitric or sulfuric acid) which is very detrimental to carbon structures since the functional groups attach to the carbon through breakage of the surface double bonds. [20] We explored the possibility of a soft functionalization procedure with the CNPs containing the highest amount of C-H groups. UV irradiation was used to convert the C-H groups to the carboxyl groups.…”

Section: Functionalization Of Carbonmentioning

confidence: 99%

Effects of Deposition Conditions on the Structure and Chemical Properties of Carbon Nanopipettes

Vitol¹,

Schrlau²,

Bhattacharyya³

et al. 2009

Chemical Vapor Deposition

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Carbon nanopipettes (CNPs) are integrated devices combining a nanometer-size carbon tip with a glass pipette. The carbon tip is produced by catalytic CVD. In this paper, it is demonstrated that the structure of the CNPs can be controlled by varying the synthesis parameters. Increased carbon graphitization is observed as the synthesis temperature increases from 890 8C to 950 8C. A similar effect is achieved by lowering the carbon precursor (methane) concentration from 60% to 20%. Changes in the amount of catalyst do not have a significant effect on the carbon graphitization. At the same time, CNPs with relatively large amounts of hydrogen bonds on the surface are obtained by using a high methane concentration. This finding is used to facilitate the functionalization of the CNPs with gold nanoparticles.

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Chemistry of Carbon Nanotubes

Cited by 10 publications

References 693 publications

The Structure and Chemical Composition of the Cr and Fe Pyrolytic Coatings on the MWCNTs’ Surface According to NEXAFS and XPS Spectroscopy

The Structure and Chemical Composition of the Cr and Fe Pyrolytic Coatings on the MWCNTs’ Surface According to NEXAFS and XPS Spectroscopy

Studies of Buried Layers and Interfaces of Tungsten Carbide Coatings on the MWCNT Surface by XPS and NEXAFS Spectroscopy

Effects of Deposition Conditions on the Structure and Chemical Properties of Carbon Nanopipettes

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