A Catalytic Reaction Inside a Single‐Walled Carbon Nanotube

Shiozawa, Hidetsugu; Pichler, Thomas; Grüneis, A.; Pfeiffer, R.; Kuzmany, H.; Liu, Zheng; Suenaga, Kazu; Kataura, Hiromichi

doi:10.1002/adma.200701466

Cited by 183 publications

(279 citation statements)

References 28 publications

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“…40 Similarly, Shiozawa et al estimated that 0.14 electrons were transferred from confined [FeCp 2 ] to SWCNTs per [FeCp 2 ] molecule according to a shift to a higher binding energy in the ultraviolet photoemission spectra (Figure 8b). 41 Lee et al observed a modified electronic structure of the nanotube in CNT-encapsulated Gd metallofullerenes, as evidenced by low-temperature scanning tunneling microscopy. 42 The above results demonstrate that an electronic interaction exists between metal species and the CNT surfaces and the strength can vary with metals and with the size of CNTs.…”

Section: Toward Understanding the Confinement Effects In Catalysismentioning

confidence: 99%

The Effects of Confinement inside Carbon Nanotubes on Catalysis

2011

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T he unique tubular morphology of carbon nanotubes (CNTs) has triggered wide research interest. These structures can be used as nanoreactors and to create novel composites through the encapsulation of guest materials in their well-defined channels. The rigid nanotubes restrict the size of the encapsulated materials down to the nanometer and even the subnanometer scale. In addition, interactions may develop between the encapsulated molecules and nanomaterials and the CNT surfaces. The curvature of CNT walls causes the π electron density of the graphene layers to shift from the concave inner to the convex outer surface, which results in an electric potential difference. As a result, the molecules and nanomaterials on the exterior walls of CNTs likely display different properties and chemical reactivities from those confined within CNTs. Catalysis that utilizes the interior surface of CNTs was only explored recently. An increasing number of studies have demonstrated that confining metal or metal oxide nanoparticles inside CNTs often leads to a different catalytic activity with respect to the same metals deposited on the CNT exterior surface. Furthermore, this inside and outside activity difference varies based on the metals used and the reactions catalyzed.In this Account, we describe the efforts toward understanding the fundamental effects of confining metal nanoparticles inside the CNT channels. This research may provide a novel approach to modulate their catalytic performance and promote rational design of catalysts. To achieve this, we have developed strategies for homogeneous dispersion of nanoparticles inside nanotubes. Because researchers have previously demonstrated the insertion of nanoparticles within larger nanotubes, we focused specifically on multiwalled carbon nanotubes (MWCNTs) with an inner diameter (i.d.) smaller than 10 nm and double-walled carbon nanotubes (DWCNTs) with 1.0À1.5 nm i.d. The results show that CNTs with well-defined morphology and unique electronic structure of CNTs provide an intriguing confinement environment for catalysis.

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Section: Toward Understanding the Confinement Effects In Catalysismentioning

confidence: 99%

The Effects of Confinement inside Carbon Nanotubes on Catalysis

2011

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“…This demonstrates a remarkable property of carbon nanotubes to act not only as nanoreactors constraining the space around the chemical reaction and templating the formation of nanoclusters or the growth of nanoribbons, but also as electrically active host-structures lending their electrons when they are required for a chemical reaction to occur inside SWNT, and retrieving electrons back when they are no longer required by the guest-species. In summary, carbon nanotubes are becoming an increasingly important class of nanoscale containers and reactors, where the pathways of chemical reactions can change significantly as a result of the restricted space of the reaction [5][6][7][8][9][10][11][12][13][14][15][16][17], or due to the interactions between the reactant molecules or catalyst particles with the host-nanotube [23,24]. Being highly conducting and having a symmetric distribution of filled and empty electronic states, SWNT possess remarkable electric properties and a unique ability to donate or accept electrons, which make nanotubes distinct among other nanocontainers and nanoreactors.…”

Section: Equationmentioning

confidence: 99%

Carbon Nanotubes as Electrically Active Nanoreactors for Multi-Step Inorganic Synthesis: Sequential Transformations of Molecules to Nanoclusters and Nanoclusters to Nanoribbons

et al. 2016

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In organic synthesis, the composition and structure of products are predetermined by the reaction conditions; however, the synthesis of well-defined inorganic nanostructures often presents a significant challenge yielding non-stoichiometric or polymorphic products. In this study, confinement in the nanoscale cavities of single-walled carbon nanotubes (SWNT) provides a new approach for multi-step inorganic synthesis where sequential chemical transformations take place within the same nanotube. In the first step, SWNT donate electrons to the reactant iodine molecules (I2) transforming them to iodide anions (I -). These then react with metal hexacarbonyls (M(CO)6, M = Mo or W) in the next step yielding anionic nanoclusters [M6I14] 2-, the size and composition of which are strictly dictated by the nanotube cavity, as demonstrated by aberration corrected high resolution transmission electron microscopy (AC-HRTEM), scanning transmission electron microscopy (STEM) and energy dispersive X-ray (EDX) spectroscopy. Atoms in the nanoclusters [M6I14] 2-are arranged in a perfect octahedral geometry and can engage in further chemical reactions within the nanotube, either reacting with each other leading to a new polymeric phase of molybdenum iodide [Mo6I12]n, or with hydrogen sulphide gas giving rise to nanoribbons of molybdenum/tungsten disulphide [MS2]n in the third step of the synthesis. Electron microscopy measurements demonstrate that the products of the multi-step inorganic transformations are precisely controlled by the SWNT nanoreactor, with complementary Raman spectroscopy revealing the remarkable property of SWNT to act as a reservoir of electrons during the chemical transformation. The electron transfer from the hostnanotube to the reacting guest-molecules is essential for stabilising the anionic metal iodide 2 nanoclusters and for their further transformation to metal disulphide nanoribbons synthesised in the nanotubes in high yield.Keywords: Carbon Nanotube, Charge Transfer, Nanoparticle, Nanoreactor, Nanoribbon Single-walled carbon nanotubes (SWNT) are among the most effective and universal containers for molecules. Provided that the internal diameter of the host-nanotube is wider than the critical diameter of the guest-molecule, the insertion of molecules into SWNT is spontaneous and, in some cases, such as fullerenes and their derivatives, irreversible due to the ubiquitous van der Waals forces dominating the host guest interactions between the nanotube and molecules [1]. Fullerenes [2,3] or organic molecules [4][5][6][7][8][9][10] encapsulated in SWNT can then be triggered to react inside the nanotube to form unusual oligomers and polymers [11][12][13], graphene nanoribbons [14][15][16], nanotubes [8,17] or extraordinary molecular nanodiamonds [9]. These examples clearly demonstrate the use of SWNT as nanoscale chemical reactors, where the structure of the macromolecular product can be precisely controlled by spatial confinement of the reactions in the nanotube channel.In contrast to organic molecules,...

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“…Very soon after their discovery the nanotubes were proposed as possible nano sized vessels for chemical reactions [23,24]. Although this progress has been partly hindered due to difficulties to probe the reactions inside the single walled carbon nanotubes (SWCNTs) some experimental studies in this direction have been reported lately [15,[25][26][27][28]. As suggested by McIntosh et al the nanotubes encapsulating the diamondoids may both guide the molecules into an ordered arrangement and in particular suppress the free rotation of the diamondoids [3].…”

Section: Introductionmentioning

confidence: 99%

Confined adamantane molecules assembled to one dimension in carbon nanotubes

Yao

Stenmark

Abou-Hamad

et al. 2011

Carbon

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We have encapsulated adamantane (C 10 H 16 ) in single-and multi walled carbon nanotubes.Adamantane is a high symmetry cage like molecule with point group symmetry, T d and can be considered as a hydrogen-terminated diamond fragment. We confirmed and identified the successful filling by high resolution transmission electron microscopy, 13 C nuclear magnetic resonance, and infrared and Raman spectroscopy. 13C nuclear magnetic resonance of the adamantane filled nanotubes reveals that the adamantane molecules stop rotating after encapsulation. A blue-shift of the Raman active radial breathing modes of the carbon nanotubes supports this and suggests a significant interaction between encapsulated adamantane molecules and the single wall nanotubes. The encapsulated adamantane molecules exhibit red shifted infrared C-H vibration modes which we assign to a slight elongation of the C-H bonds. We observe both a nanotube diameter dependence of the adamantane fill ratio and a release rate of adamantane from the CNTs that depends on the CNT diameters.

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A Catalytic Reaction Inside a Single‐Walled Carbon Nanotube

Cited by 183 publications

References 28 publications

The Effects of Confinement inside Carbon Nanotubes on Catalysis

The Effects of Confinement inside Carbon Nanotubes on Catalysis

Carbon Nanotubes as Electrically Active Nanoreactors for Multi-Step Inorganic Synthesis: Sequential Transformations of Molecules to Nanoclusters and Nanoclusters to Nanoribbons

Confined adamantane molecules assembled to one dimension in carbon nanotubes

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