Reducing Reaction of Fe<sub>3</sub>O<sub>4</sub> in Nanoscopic Reactors of a-CNTs

Cao, Fangyu; Zhong, Kaifu; Gao, Aimei; Chen, Changle; Li, Quanxin; Chen, Qianwang

doi:10.1021/jp0661037

Cited by 31 publications

(26 citation statements)

References 25 publications

(36 reference statements)

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“…[69][70][71][72][73] Considering the simplicity and universality, the impregnation method is the most suitable approach for catalyst preparation. The preparation of Fe, Co and Ni NPs inside or outside CNTs could be all achieved via the aqueous process, [74][75][76][77][78][79][80] which typically involves the pretreatment of CNTs and the dispersion of metal NPs on CNTs.…”

Section: Introductionmentioning

confidence: 99%

Recent Advances on the Design of Group VIII Base-Metal Catalysts with Encapsulated Structures

et al. 2015

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Inexpensive group VIII metal (i.e., Fe, Co, and Ni)-based solid catalysts have been widely used in various energy transformation processes such as Fisher-Tropsch (F-T) synthesis, reforming and water-gas shift reactions. The emerging encapsulation strategy, which represents active metal species are coated by protective shell or matrix, has been demonstrated as a powerful means to promote the catalytic performance (i.e., activity, stability and selectivity) of Fe-, Co-and Ni-based catalysts due to synergic effects from the well-defined structures. This review describes recent progress on the design and synthesis of encapsulated group VIII base-metal nanomaterials developed for energy and environmental catalysis including syngas conversion, CO 2 dry reforming, steam reforming, methane conversion and NH 3 decomposition. We start with an introduction of the catalysts with different encapsulating structures (e.g., core@shell, yolk@shell, core@tube, mesoporous structures and lamellar structures). Then, the synthetic methods of Fe-, Co-and Ni-based catalysts with encapsulated structures are described in detail. The functions of encapsulation structures in catalysis, including protecting metal nanoparticles (NPs) from sintering, promoting the activity due to the confinement effect and intensifying reaction processes in the form of multifunctional catalysts, are discussed respectively. Our perspectives regarding the challenges and opportunities for future research in the field are also provided.

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Section: Introductionmentioning

confidence: 99%

Recent Advances on the Design of Group VIII Base-Metal Catalysts with Encapsulated Structures

et al. 2015

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“…Besides, heat treatment of the Fe 3 O 4 /CNT nanofibres at various temperatures was performed under high-purity N 2 stream. It can be found from XRD patterns of the solid products that reduction of Fe 3 O 4 happened at a temperature (called Tc) above 500 o C, and Fe 3 O 4 kept stable below Tc [13]. The result of this investigation indicates that the carbon shell prevent the ferrite core from being oxidized, making Fe 3 O 4 /CNT nanocomposite available as microwave absorber even under relatively high temperatures.…”

Section: Resultsmentioning

confidence: 75%

Alignment of Fe₃O₄-Carbon Coaxial Nanofibres in a Polymer for Improving Microwave Absorption

Chen

Cao

2007

2007 7th IEEE Conference on Nanotechnology (IEEE NANO)

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A composite with highly aligned array of Fe 3 O 4 /CNT coaxial nanofibres in poly (methyl methacrylate) matrix has been fabricated under low magnetic field. The structure and microwave absorption properties of the product were investigated using various techniques, such as field emission scanning electron microanalysis, transmission electron microscopy and vector network analyzer. It was found that microwave absorption of the magnetically aligned composite at 8.5-12.5 GHz was evidently enhanced, comparing with the composite without magnetic treatment. The enhancement mechanism is also discussed based on magnetization theory.

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“…Here, iron nanoparticles are thought to be the actual catalysts existing on the nanowire because the Fe 3 O 4 nanoparticles used in the growth process are usually reduced to Fe nanoparticles at high temperature (T >900 8C) in H 2 atmosphere according to our observations and some previous literature. [27,28] As seen in Figure 4, the nanowires in the two contact modes have different band diagrams for their conductivity measurements. For Type-I nanostructures, the first contact barrier results from double hetero-junction barriers between the n-type heavily doped silicon substrate and the boron nanowire, and the second barrier is related to the contact resistance between the nanowire and the tungsten probe.…”

Section: Resultsmentioning

confidence: 99%

Effect of Contact Mode on the Electrical Transport and Field‐Emission Performance of Individual Boron Nanowires

Fei

et al. 2010

Adv Funct Materials

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Vapor–liquid–solid processing of boron nanowires (BNWs) can be carried out either using a bottom‐up or top‐down growth mode, which results in different contact modes between the nanowire and the substrate. The contact mode may strongly affect the electrical transport and field‐emission performance of the individual boron nanowires grown on a Si substrate. The electrical transport and field‐emission characteristics of individual boron nanowires of different contact modes are investigated in situ using a scanning electron microscope. The contact barriers are very distinct for the different contact modes. Moreover, the transition from a “contact‐limited” to a “bulk‐limited” field‐emission (FE) process is demonstrated in nanoemitters for the first time, and the proposed improved metal–insulator–vacuum (MIV) model may better illustrate the nonlinear behavior of the Fowler‐Nordheim (FN) plots in these nanoscale systems. Individual BNWs with different contact modes have a discrepancy in their emission stability and vacuum breakdown characteristics though they have similar aspect ratios, which suggests that their electrical transport and field‐emission performance are closely related to their contact mode. Boron nanowires grown in the base‐up mode have better field‐emission performances and are more beneficial than those grown in the top‐down mode for various device applications.

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Reducing Reaction of Fe₃O₄ in Nanoscopic Reactors of a-CNTs

Cited by 31 publications

References 25 publications

Recent Advances on the Design of Group VIII Base-Metal Catalysts with Encapsulated Structures

Recent Advances on the Design of Group VIII Base-Metal Catalysts with Encapsulated Structures

Alignment of Fe₃O₄-Carbon Coaxial Nanofibres in a Polymer for Improving Microwave Absorption

Effect of Contact Mode on the Electrical Transport and Field‐Emission Performance of Individual Boron Nanowires

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Reducing Reaction of Fe3O4 in Nanoscopic Reactors of a-CNTs

Cited by 31 publications

References 25 publications

Recent Advances on the Design of Group VIII Base-Metal Catalysts with Encapsulated Structures

Recent Advances on the Design of Group VIII Base-Metal Catalysts with Encapsulated Structures

Alignment of Fe3O4-Carbon Coaxial Nanofibres in a Polymer for Improving Microwave Absorption

Effect of Contact Mode on the Electrical Transport and Field‐Emission Performance of Individual Boron Nanowires

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Reducing Reaction of Fe₃O₄ in Nanoscopic Reactors of a-CNTs

Alignment of Fe₃O₄-Carbon Coaxial Nanofibres in a Polymer for Improving Microwave Absorption