Facile Autoreduction of Iron Oxide/Carbon Nanotube Encapsulates

Chen, Wei; Pan, Xiulian; Willinger, Marc Georg; Bao, Xinhe

doi:10.1021/ja056721l

Cited by 252 publications

(213 citation statements)

References 15 publications

(30 reference statements)

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“…22,26 The narrower the tubes, the more facile was the reduction of the confined Fe 2 O 3 ( Figure 3a). Facilitated reduction was also observed for Fe 3 O 4 nanowires inside CNTs.…”

Section: Gas-phase Reactionsmentioning

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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“…22,26 The narrower the tubes, the more facile was the reduction of the confined Fe 2 O 3 ( Figure 3a). Facilitated reduction was also observed for Fe 3 O 4 nanowires inside CNTs.…”

Section: Gas-phase Reactionsmentioning

confidence: 99%

The Effects of Confinement inside Carbon Nanotubes on Catalysis

2011

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“…Iron NPs possess good magnetic property and thus have been used as the magnetic cores for some drug delivery purposes [37][38][39]. Previously, Chen et al have reported the direct reduction of Fe 2 O 3 to metallic iron on the inner and external surface of CNTs [36,40]. So, the composites of Fe/CNTs were hereby chosen as the original material for the design of dual-targeted drug delivery system in this work.…”

Section: Synthesis and Characterization Of The Dual-targeted Drug Nanmentioning

confidence: 99%

Folate and iron difunctionalized multiwall carbon nanotubes as dual-targeted drug nanocarrier to cancer cells

Zhao

et al. 2011

Carbon

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“…In some other circumstances, environmental effects may lead to unexpected nanomaterial properties. In addition to changing the reduction conditions for iron oxide, [54] environmental effects include the impact of water on the atomic structure of ZnS nanoparticles [53] and phase transitions for hematite nanoparticles, [28] the influence of humidity on polymer nanocomposite structure, [55] as well as the effects of surface adsorbates on particle shape [56] and separation. [57] In summary, it is important for researchers to recognize the potential influence of analysis probes and particle environments on the characterization of nanostructured materials.…”

Section: Environmental Effectsmentioning

confidence: 99%

Characterization challenges for nanomaterials

Baer

Amonette

Engelhard

et al. 2008

Surface & Interface Analysis

123

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Nanostructured materials are increasingly subject to nearly every type of chemical and physical analysis possible. Due to their small sizes, there is a significant focus on tools with high spatial resolution. It is also natural to characterize nanomaterials using tools designed to analyze surfaces, because of their high surface area. Regardless of the approach, nanostructured materials present a variety of obstacles to adequate, useful, and needed analysis. Case studies of measurements on ceria and iron metal-core/oxide-shell nanoparticles are used to introduce some of the issues that frequently need to be addressed during analysis of nanostructured materials. We use a combination of tools for routine analysis including X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and x-ray diffraction (XRD) and apply several other methods as needed to obtain essential information. The examples provide an introduction to other issues and complications associated with the analysis of nanostructured materials including particle stability, probe effects, environmental effects, specimen handling, surface coating, contamination, and time.

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Facile Autoreduction of Iron Oxide/Carbon Nanotube Encapsulates

Abstract: Facile autoreduction of iron oxide encapsulated within carbon nanotubes has been observed at a temperature 200 degrees C lower than those on the outer surface. This opens a new route to tune the state of confined nanoparticles of d-band metals by the confinement of CNTs.

Cited by 252 publications

References 15 publications

The Effects of Confinement inside Carbon Nanotubes on Catalysis

The Effects of Confinement inside Carbon Nanotubes on Catalysis

Folate and iron difunctionalized multiwall carbon nanotubes as dual-targeted drug nanocarrier to cancer cells

Characterization challenges for nanomaterials

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