Tomography Using the Transmission Electron Microscope

Midgley, Paul A.

doi:10.1007/1-4020-8006-9_19

Cited by 4 publications

(1 citation statement)

References 91 publications

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“…Electron tomography makes it possible to study the three-dimensional nanotube-metal contact geometry which determines the electrical contact resistance to the nanotubes (courtesy of J. Cha, M. Weyland, and D. Muller, 2006). (2003), Midgley (2005), Weyland et al (2006) and Kawase et al (2007). gress of these techniques, which has culminated in a remarkable near-…”

Section: Peter W Hawkes John Ch Spencementioning

confidence: 99%

Science of Microscopy

Hawkes¹,

Spence²

2007

121

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tion with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identifi ed as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. springer.com 9 8 7 6 5 4 3 2 (corrected printing, 2008) LLC,

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Section: Peter W Hawkes John Ch Spencementioning

confidence: 99%

Science of Microscopy

Hawkes¹,

Spence²

2007

121

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Substrate Size‐Selective Catalysis with Zeolite‐Encapsulated Gold Nanoparticles

et al. 2010

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Substrate Size‐Selective Catalysis with Zeolite‐Encapsulated Gold Nanoparticles

et al. 2010

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Over the years, many strategies have been developed to address the problem of sintering of nanoparticle catalysts, [1] including encapsulating metal nanoparticles in protective shells, [2][3][4] and trapping nanoparticles in the cavities of certain zeolites in post-synthesis steps. [5][6][7][8] In general, materials that contain metal nanoparticles that are only accessible via zeolite micropores are intriguing, specifically, but not exclusively, for catalytic applications. The encapsulation of carbon nanoparticles during zeolite crystallization is a well-known approach for making carbon-zeolite composites that afford mesoporous zeolites after combustion.[9-11] Herein, we show that metal nanoparticles can also be encapsulated during zeolite crystallization, as exemplified by silicalite-1 crystals that are embedded with circa 1-2 nm-sized gold nanoparticles that remain stable and catalytically active after calcination in air at 550 8C. Moreover, we show that the encapsulated gold nanoparticles are only are accessible through the micropores of the zeolite, which makes this material a substrate-size selective oxidation catalyst.Currently, more than 175 different zeolite structures have been reported, [12] and these can be tuned according to the desired acidity and/or redox properties. Expanding the scope from pure zeolites to hybrid materials, by combining the properties of zeolites with other components, significantly widens the field of zeolite materials design. Aside from posttreatment methods, two types of approaches have been pursued for preparing hybrid zeolite-nanoparticle materials. The first type of approach involves crystallization of the zeolite from a gel that contains metal ions that are immobilized in the zeolite during crystallization. [13][14] With this kind of approach, it is very difficult to control the properties of the non-zeolite component in terms of, for example, particle size. The other type of approach is to first synthesize the nonzeolite component and subsequently encapsulate this in the individual zeolite crystals during crystallization. Indeed, this strategy is also well-known and an entire family of materials, known as mesoporous or hierarchical zeolite crystals, are based on the embedding of carbon nanoparticles, nanofibers, nanotubes, or other nanostructures during zeolite crystallization (and subsequent combustion) in a process known as carbon templating. [9-11, 15, 16] Concerning the embedding of metal nanoparticles in zeolites, Hashimoto et al. reported a top down approach that features downsizing gold flakes to approximately 40 nm particles by laser ablation, and subsequent encapsulation of these particles during crystallization.[17] A reduction in particle size by one order of magnitude is necessary for an efficient use of costly noble metals in catalytic applications. However, a reduction of the particle size enhances the tendency for sintering, owing to the increase in surface free energy. To mitigate this problem, we report herein a bottom-up approach for the preparation of h...

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Tomography Using the Transmission Electron Microscope

Cited by 4 publications

References 91 publications

Science of Microscopy

Science of Microscopy

Substrate Size‐Selective Catalysis with Zeolite‐Encapsulated Gold Nanoparticles

Substrate Size‐Selective Catalysis with Zeolite‐Encapsulated Gold Nanoparticles

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