Opening carbon nanotubes with oxygen and implications for filling
TL;DR: In this paper, it was shown that the oxidation of carbon nanotubes in air for short durations above about 700 °C results in the etching away of the tube caps and the thinning of tubes through layer-by-layer peeling of the outer layers, starting from the cap region.
Abstract: CAPPED hollow carbon nanotubes1,2 can be modified into nanocomposite fibres by simultaneous opening of the caps (by heating in the presence of air and lead metal) and filling of the interior with an inorganic phase3. To generalize this approach, greater understanding is needed of the reaction mechanism between the tube caps and oxygen. Here we report that the oxidation of carbon nanotubes in air for short durations above about 700 °C results in the etching away of the tube caps and the thinning of tubes through layer-by-layer peeling of the outer layers, starting from the cap region. The oxidation reaction follows an Arrhenius-type relation with an activation energy barrier of about 225 kJ mol−1 in air. Heating of closed nanotubes with an oxide (Pb3O4) in an inert atmosphere lowers the activation barrier for the reaction and opening of the tubes occurs at lower temperatures. Contrary to intuition, however, open tubes are much more difficult to fill with inorganic materials than in the one-step filling of tubes reported previously3. But various other experiments might be possible in the inner nano-cavities of the open tubes such as studies of catalysis and of low-dimensional chemistry and physics.
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TL;DR: In this article, the authors reported the synthesis of abundant single-shell tubes with diameters of about one nanometre, whereas the multi-shell nanotubes are formed on the carbon cathode.
Abstract: CARBON nanotubes1 are expected to have a wide variety of interesting properties. Capillarity in open tubes has already been demonstrated2–5, while predictions regarding their electronic structure6–8 and mechanical strength9 remain to be tested. To examine the properties of these structures, one needs tubes with well defined morphologies, length, thickness and a number of concentric shells; but the normal carbon-arc synthesis10,11 yields a range of tube types. In particular, most calculations have been concerned with single-shell tubes, whereas the carbon-arc synthesis produces almost entirely multi-shell tubes. Here we report the synthesis of abundant single-shell tubes with diameters of about one nanometre. Whereas the multi-shell nanotubes are formed on the carbon cathode, these single-shell tubes grow in the gas phase. Electron diffraction from a single tube allows us to confirm the helical arrangement of carbon hexagons deduced previously for multi-shell tubes1.
8,018 citations
TL;DR: Department of Materials Science, University of Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Triesteadays.
Abstract: Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy
3,886 citations
TL;DR: In this article, a gas can condense to high density inside narrow, single-walled nanotubes (SWNTs) under conditions that do not induce adsorption within a standard mesoporous activated carbon.
Abstract: Pores of molecular dimensions can adsorb large quantities of gases owing to the enhanced density of the adsorbed material inside the pores1, a consequence of the attractive potential of the pore walls. Pederson and Broughton have suggested2 that carbon nanotubes, which have diameters of typically a few nanometres, should be able to draw up liquids by capillarity, and this effect has been seen for low-surface-tension liquids in large-diameter, multi-walled nanotubes3. Here we show that a gas can condense to high density inside narrow, single-walled nanotubes (SWNTs). Temperature-programmed desorption spectrosocopy shows that hydrogen will condense inside SWNTs under conditions that do not induce adsorption within a standard mesoporous activated carbon. The very high hydrogen uptake in these materials suggests that they might be effective as a hydrogen-storage material for fuel-cell electric vehicles.
3,558 citations
3,052 citations
TL;DR: In this article, the effect of oxidation on the structural integrity of multiwalled carbon nanotubes through acidic (nitric acid and a mixture of sulfuric acid and hydrogen peroxide) and basic (ammonium hydroxide/hydrogen peroxide), agents has been studied.
2,454 citations
Cites background from "Opening carbon nanotubes with oxyge..."
...[35] Ajayan PM, Ebbesen TW, Ichihashi T, Iijima S, Tanigaki K, Hura H....
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References
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NEC1
TL;DR: Iijima et al. as mentioned in this paper reported the preparation of a new type of finite carbon structure consisting of needle-like tubes, which were produced using an arc-discharge evaporation method similar to that used for fullerene synthesis.
Abstract: THE synthesis of molecular carbon structures in the form of C60 and other fullerenes1 has stimulated intense interest in the structures accessible to graphitic carbon sheets. Here I report the preparation of a new type of finite carbon structure consisting of needle-like tubes. Produced using an arc-discharge evaporation method similar to that used for fullerene synthesis, the needles grow at the negative end of the electrode used for the arc discharge. Electron microscopy reveals that each needle comprises coaxial tubes of graphitic sheets, ranging in number from 2 up to about 50. On each tube the carbon-atom hexagons are arranged in a helical fashion about the needle axis. The helical pitch varies from needle to needle and from tube to tube within a single needle. It appears that this helical structure may aid the growth process. The formation of these needles, ranging from a few to a few tens of nanometres in diameter, suggests that engineering of carbon structures should be possible on scales considerably greater than those relevant to the fullerenes. On 7 November 1991, Sumio Iijima announced in Nature the preparation of nanometre-size, needle-like tubes of carbon — now familiar as 'nanotubes'. Used in microelectronic circuitry and microscopy, and as a tool to test quantum mechanics and model biological systems, nanotubes seem to have unlimited potential.
39,086 citations
NEC1
TL;DR: In this article, the authors used a variant of the standard arc-discharge technique for fullerene synthesis under a helium atmosphere, where a carbonaceous deposit formed on one of the graphite rods, consisting of a macroscopic (diameter of about 5 mm) cylinder.
Abstract: INTEREST in carbon fibres1,2 has been stimulated greatly by the recent discovery of hollow graphitic tubules of nanometre dimensions3. There has been much speculation about the properties and potential application of these nanotubes4–8. Theoretical studies predict that their electronic properties will depend on their diameter and degree of helicity4,5. Experimental tests of these ideas has been hampered, however, by the lack of macroscopic quantities of the material. Here we report the synthesis of graphitic nanotubes in gram quantities. We use a variant of the standard arc-discharge technique for fullerene synthesis under a helium atmosphere. Under certain conditions, a carbonaceous deposit forms on one of the graphite rods, consisting of a macroscopic (diameter of about 5 mm) cylinder in which the core comprises pure nanotubes and nanoscale particles in high yield. The purity and yield depend sensitively on the gas pressure in the reaction vessel. Preliminary measurements of the conductivity of the bulk nanotube material indicate a conductivity of about 100 S cm–11.
2,908 citations
NEC1
TL;DR: In this article, the authors describe experiments in which annealing of the tubules in the presence of liquid lead results in opening of the capped tube ends and subsequent filling of the tubes with molten material through capillary action.
Abstract: THE recent discovery1 and bulk synthesis2 of nanometre-scale carbon tubules has led to much speculation about possible uses of these graphitic structures3–5. Broughton and Pederson predicted on the basis of computer simulations that open nanotubes may be filled with liquid by capillary suction6. Here we describe experiments in which annealing of the tubules in the presence of liquid lead results in opening of the capped tube ends and subsequent filling of the tubes with molten material through capillary action. The nanotubes thus act as moulds for the fabrication of (possibly metallic) wires, some of which are less than two nanometres in diameter.
1,331 citations
Book•
12 Jul 1988
TL;DR: In this paper, the authors introduce Graphite Fibers and Filaments and present applications of graphite fibers and filament for applications in computer vision, artificial intelligence, and medical applications.
Abstract: Contents: Introductory Material on Graphite Fibers and Filaments.- Synthesis of Graphite Fibers and Filaments.- Structure.- Lattice Properties.- Thermal Properties.- Mechanical Properties.- Electronic Structure.- Electronic and Magnetic Properties.- High Temperature Properties.- Intercalation of Graphite Fibers and Filaments.- Ion Implantation of Graphite Fibers and Filaments.- Applications of Graphite Fibers and Filaments.- References.- Subject Index.
572 citations
TL;DR: In this article, the emphasis is on the high electron affinity of buckminsterfullerene, where reductions, nucleophilic additions, and oxidative additions of low-valent transition metals are considered as the sole avenues to fullerene C[sub 60] functionalization and modification.
Abstract: In this account, the emphasis is on the high electron affinity of buckminsterfullerene, where reductions, nucleophilic additions, and oxidative additions of low-valent transition metals are considered as the sole avenues to fullerene C[sub 60] functionalization and modification. However, it should be mentioned that electrophilic additions have also been reported.
521 citations