Identification of Electron Donor States in N-Doped Carbon Nanotubes

Czerw, R.; Terrones, Mauricio; Charlier, Jean‐Christophe; Blase, Xavier; Foley, Brian M.; Kamalakaran, R.; Grobert, Nicole; Terrones, Humberto; Tekleab, D.; Ajayan, Pulickel M.; Blau, Werner J.; Rühle, M.; Carroll, D. L.

doi:10.1021/nl015549q

Cited by 740 publications

(553 citation statements)

References 31 publications

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“…For instance, doping with boron introduced acceptor states near the valence band edge 46 while nitrogen-doping added electron donor states near the conduction band edge. 47 N-doped MWCNTs were recently demonstrated to enhance significantly the ammonia decomposition activity of Ru nanoparticles dispersed on their exterior walls. 48 Precise manipulation of the location of heteroatoms either exclusively on interior or exterior walls of CNTs may allow fine-tuning of catalytic properties.…”

Section: Conclusion and Prospectsmentioning

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: Conclusion and Prospectsmentioning

confidence: 99%

The Effects of Confinement inside Carbon Nanotubes on Catalysis

2011

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“…The amount of doped nitrogen can be tuned in the range of N/C atomic ratio < 0.1 [98][99][100][101]. A unique feature of the N-doped CNTs synthesized by the AAO template method is that their hollow cores are empty, which is quite different from the bamboo-like structures of the N-doped CNTs by the conventional synthesis methods [95,[106][107][108]. And such N-doped AAO-CNTs show advantage in the filling of foreign matters.…”

Section: Hetero Atom Doping Of the Aao-cntsmentioning

confidence: 99%

“…When an electric field is applied, metal ions in the electrolyte solution migrate and are deposited onto an electrode by passing a current through an electrochemical cell. Therefore, metals can be filled into the cavity of AAOCNTs by using the electrodeposition method under a direct current [41,128,129] or alternating current [106]. In general, a layer of Au is first deposited on the surface of a both-side open AAO film using ion sputtering technique.…”

Section: Electrodepositionmentioning

confidence: 99%

“…This novel bottom-up filling opens a route to controllable filling of materials of interest into CNTs with one open end. Recently, aligned Ni nanoparticles array are also reported to be encapsulated in the channel of AAO-CNT using alternating current by decreasing the thickness of the barrier layer [106]. At the same time, magnetic metal or alloy filled in the cavity of CNTs is responsive to magnetic field even after a long-term storage in water.…”

Section: Electrodepositionmentioning

confidence: 99%

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Carbon nanotubes prepared by anodic aluminum oxide template method

et al. 2011

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One of the most unique structural characteristics of carbon nanotubes (CNTs) differentiating from other carbon materials is their hollow nanochannles, which can be utilized for encapsulating and loading foreign matters. The anodic aluminum oxide (AAO) template technique enables the diameter, length, and cap structure control of the replicated CNTs, and thus shows advantages in pore structure control over the traditional CNT growth approaches. This review details the synthesis of CNTs with tunable diameter, length, wall thickness, and crystalline by using the AAO template method. The doping of heteroatoms and filling of foreign matters into AAO-CNTs are also addressed. Moreover, the main challenges and developing trends of the AAO template method are discussed.carbon nanotubes (CNTs), anodic aluminum oxide (AAO) template method, controllability Citation:Hou P X, Liu C, Shi C, et al. Carbon nanotubes prepared by anodic aluminum oxide template method.

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“…Previous studies have shown that it is possible to alter both mechanical and electronic properties of nanotubes by modifying their side walls physically and chemically (deformations, defects, B-and N-doping, functional side groups). 5,[10][11][12][13][14][15] Furthermore, one can use noncovalently attached supermolecules for isolating CNTs and blocking their self-adhesion scheme in polar solvents. 16,17 Crown ethers and cyclodextrins are interesting molecules in this respect, because they have hydrophobic and hydrophilic parts and tend to attach to organic macromolecules.…”

Section: Introductionmentioning

confidence: 99%

Electronic Properties of Single-Walled Carbon Nanotubes inside Cyclic Supermolecules

2006

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Possible ways for manipulating carbon nanotubes (CNTs) with cyclic supermolecules are studied using density functional theory. Electronic structure calculations with structure optimizations have been performed for the (4,4) and (8,0) single-walled carbon nanotubes (SWNTs) complexed with crown ethers as well as for the (4,0) SWNT with -cyclodextrin. A slight polarization of charge in both the nanotube and the supermolecule is observed upon rotaxane complexation, but the interaction is mainly repulsive, and the systems stay 2.8-3.5 Å apart. The supermolecule does not affect the electronic band structure of the nanotube significantly within such a configuration. The situation differs noticeably for chemically cross-linked SWNTs and crown ethers, where a peak arises at the Fermi energy in the density of states. As a result, the band gap of semiconducting CNT(8,0) (0.5 eV) vanishes, and a new conduction channel opens for the metallic CNT(4,4).

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Identification of Electron Donor States in N-Doped Carbon Nanotubes

Cited by 740 publications

References 31 publications

The Effects of Confinement inside Carbon Nanotubes on Catalysis

The Effects of Confinement inside Carbon Nanotubes on Catalysis

Carbon nanotubes prepared by anodic aluminum oxide template method

Electronic Properties of Single-Walled Carbon Nanotubes inside Cyclic Supermolecules

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