Analysis of the structure and chemical properties of some commercial carbon nanostructures

Tessonnier, Jean‐Philippe; Rosenthal, Dirk; Hansen, Thomas Willum; Heß, Christian; Schuster, Manfred Erwin; Blume, Raoul; Girgsdies, Frank; Pfänder, Norbert; Timpe, Olaf; Su, Dang Sheng; Schlögl, Robert

doi:10.1016/j.carbon.2009.02.032

Cited by 311 publications

(284 citation statements)

References 91 publications

(126 reference statements)

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“…However, while MG presented an intense and sharp peak, the diffraction peak of CNT was broad and it was slightly shifted to higher angles. This is consistent with the different interlayer distance due to the curvature of the layers which also leads to a different order degree [15]. Finally, the XRD profile of AC showed a broad hump at 2θ = 26º, this confirming the amorphous nature of this support.…”

Section: Support Characterizationsupporting

confidence: 79%

Ir supported over carbon materials for the selective hydrogenation of chloronitrobenzenes

et al. 2015

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In the present work we have studied the effect of carbon supports with different graphitic character (carbon nanotubes, mesoporous graphite and activated carbon) on the catalytic performance of iridium nanoparticles on the liquid phase chemoselective hydrogenation of para-chloronitrobenzene at room temperature. The effect of the oxygen groups was also evaluated by oxidizing a portion of the carbon nanotubes. The Raman and XRD spectra showed that the mesoporous graphite displayed the strongest graphitic character. The characterization of the catalysts by HR-TEM, XPS and TPR-H2, showed that the catalysts had similar particle size and that the catalysts prepared over the previously oxidized support, Ir/CNTox, was not fully reduced. The activity and selectivity achieved with the catalyst Ir/CNT was the best among the samples and the presence of irdium oxide on Ir/CNTox diminished the yield to p-chloroaniline, being the worse catalyst. The reactivity of different isomers was also studied over Ir/CNT and it followed the order m > o > p. This is a previous version of the article published in Catalysis Today. 2015Today. , 249: 72-78. doi:10.1016Today. /j.cattod.2014 Highlights -Ir catalysts supported on carbon materials with different graphitic character.-The effect of oxygen groups in carbon nanotubes has been evaluated.-Ir/CNT shows the best catalytic performance in p-chloronitrobenzene hydrogenation.-The reactivity of different isomers on Ir/CNT was m > o > p. AbstractIn the present work we have studied the effect of carbon supports with different graphitic character (carbon nanotubes, mesoporous graphite and activated carbon) on the catalytic performance of iridium nanoparticles on the liquid phase chemoselective hydrogenation of para-chloronitrobenzene at room temperature. The effect of the oxygen groups was also evaluated by oxidizing a portion of the carbon nanotubes. TheRaman and XRD spectra showed that the mesoporous graphite displayed the strongest graphitic character. The characterization of the catalysts by HR-TEM, XPS and TPR-H 2 , showed that the catalysts had similar particle size and that the catalysts prepared over the previously oxidized support, Ir/CNTox, was not fully reduced. The activity and selectivity achieved with the catalyst Ir/CNT was the best among the samples and the presence of irdium oxide on Ir/CNTox diminished the yield to p-chloroaniline, *Manuscript Click here to view linked References being the worse catalyst. The reactivity of different isomers was also studied over Ir/CNT and it followed the order m > o > p.

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Section: Support Characterizationsupporting

confidence: 79%

Ir supported over carbon materials for the selective hydrogenation of chloronitrobenzenes

et al. 2015

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“…This can be sensitively observed by a microelectrophoretic method. MWCNTs usually have a negative zeta potential under neutral solution conditions [54,55]. As expected, the electrophoretic mobility (EM) of the pristine CP was investigated it can be also hypothesized that electrostatic interactions play a role in the uptake of PFOA.…”

Section: Resultsmentioning

confidence: 74%

Surface-associated metal catalyst enhances the sorption of perfluorooctanoic acid to multi-walled carbon nanotubes

Schäffer

Séquaris

et al. 2012

Journal of Colloid and Interface Science

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Surface-associated metal catalyst enhances the sorption of perfluorooctanoic acid to multi-walled carbon nanotubes Journal of Colloid and Interface Science, 377, 342-346, 2012 2 AbstractPerfluorooctanoic acid (PFOA) sorption behaviour of two commercial multi-walled carbon nanotubes (MWCNTs) (C 150 P from Bayer MaterialScience: BA and C-MWNTs from NanoTechLabs Inc.: CP) was investigated from aqueous solution. The BA nanotubes contain Co/Mn/Mg/Al catalysts both on their outer surface and in the inner bore while CP contains Fe-based catalyst typically within the tubes. The adsorption isotherms of 14 C-radiolabeled PFOA were measured by batch experiments and fitted to the Freundlich model (r 2 0.92).. The adsorption affinity and capacity on BA were significantly higher than on CP. Increasing the pH reduced the adsorption of PFOA due to the electrostatic interaction between the pH-sensitive surface and the adsorbate. Increasing NaCl concentration lead to the aggregation of the MWCNTs reducing the available surface and thus the adsorption capacity. Removal of the catalyst from the outer surface of BA changed the electrophoretic mobility from positive to negative value also decreasing the adsorbed amount of PFOA. The surface charge of the surface-associated metal catalyst favors the electrostatic sorption of PFOA. Such surface modification may be a promising way to improve the sorption capacity of MWCNTs for pollutants like PFOA and to broaden their potential application in water purification.Keywords: Perfluorooctanoic acid; multi-walled carbon nanotubes; metal catalyst; sorption Chengliang Li, Andreas Schäffer, Jean-Marie Séquaris, Krisztina László, Ajna Tóth, Etelka Tombácz, Harry Vereecken, Rong Ji, Erwin Klumpp Surface-associated metal catalyst enhances the sorption of perfluorooctanoic acid to multi-walled carbon nanotubes

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“…This model overestimates the oxygen content if one assumes the more likely case that oxygen is predominately located at the outer surface. For several carbon samples the difference between the uniform distribution and a surface layer model could be up to a factor of 30 [19]. Thus, the very high amount of oxygen in the H 2 O 2 -treated sample C2 points to more aliphatic carbon on the surface accompanied by a loss of the graphitic character.…”

Section: Xps Results Of the Oxidative Treatmentmentioning

confidence: 97%

“…2 presents the superposition of the XP spectra in the C1s region for non-heated samples A1 (untreated), C2 (H 2 O 2 -treated), D4 (ozone-treated) and additionally for sample C2 heated to 1043 K. The difference spectra between oxidized and non-activated samples (D4 and A1) and oxidized C2 (RT) and heated samples C2 (840 K) are shown at the bottom. The observation of the changes in the C1s spectra allows us to elucidate the presence of defect sites in the CNF and thus the degree of graphitization [19,25,26]. In the case of the ozone-treated sample, D4, the intensity of the peak associated with graphitic carbon (284.5 eV) decreases slightly upon going from the untreated sample to the oxygen-functionalized sample.…”

Section: Xps Results Of the Oxidative Treatmentmentioning

confidence: 99%

“…The deconvolution of the main peak in the C1s region is generally more difficult and ambiguous, as the relative contribution to the peaks from oxygenated groups compared to that from the asymmetrically shaped graphitized carbon signal is too small to be isolated directly from the spectra. Instead, C1s difference spectra were obtained by normalizing the intensity of both spectra at the minimum of the intensity between the C1s and its Mg satellites and subsequent subtraction without shifting of the binding energy [19]. The H 2 O 2 -functionalized samples always showed traces of tin oxide (binding energy of Sn 3d 5/2 is $487 eV and after partial reduction at 1040 K, BE $485 eV).…”

Section: Xpsmentioning

confidence: 99%

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Combined XPS and TPD study of oxygen-functionalized carbon nanofibers grown on sintered metal fibers

Rosenthal

Ruta

Schlögl

et al. 2010

Carbon

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A B S T R A C TA composite material consisting of carbon nanofibers (CNFs) grown on sintered metal fiber filters was modified by H 2 O 2 or plasma-generated O 3 . Coupling temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) techniques in the same UHV apparatus allowed the direct correlation of the nature of the created O-functional groups and their evolution as CO and CO 2 upon heating. The two oxidative treatments yielded different distributions of O-containing groups. The relative contribution of oxidized carbon was very low in the C1s region, hence the functional groups were more robustly analyzed through the O1s region. The comparison of the released oxygen by integration of the TPD CO, CO 2 and H 2 O spectra with the intensity loss of the XPS O1s spectra showed good agreement. In order to fit the data adequately, the set of O1s spectra was deconvoluted in at least four peaks for the differently activated samples. Finally, it was shown that functional groups formed by H 2 O 2 -treatment (mostly non-phenolic OH groups) are more thermally stable than those formed by O 3 -treatment. The latter treatment increases the concentration of carboxylic functionalities, which decompose at temperatures < 800 K;O 3 -activated CNFs should therefore show a more pronounced acidic behavior.

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Analysis of the structure and chemical properties of some commercial carbon nanostructures

Cited by 311 publications

References 91 publications

Ir supported over carbon materials for the selective hydrogenation of chloronitrobenzenes

Ir supported over carbon materials for the selective hydrogenation of chloronitrobenzenes

Surface-associated metal catalyst enhances the sorption of perfluorooctanoic acid to multi-walled carbon nanotubes

Combined XPS and TPD study of oxygen-functionalized carbon nanofibers grown on sintered metal fibers

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