Journal ArticleDOI
Atom-Resolved Imaging of Dynamic Shape Changes in Supported Copper Nanocrystals
Poul L. Hansen,Jakob Birkedal Wagner,Stig Helveg,Jens R. Rostrup-Nielsen,Bjerne S. Clausen,Henrik Topsøe +5 more
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In situ transmission electron microscopy is used to obtain atom-resolved images of copper nanocrystals on different supports, which are catalysts for methanol synthesis and hydrocarbon conversion processes for fuel cells.Abstract:
In situ transmission electron microscopy is used to obtain atom-resolved images of copper nanocrystals on different supports. These are catalysts for methanol synthesis and hydrocarbon conversion processes for fuel cells. The nanocrystals undergo dynamic reversible shape changes in response to changes in the gaseous environment. For zinc oxide-supported samples, the changes are caused both by adsorbate-induced changes in surface energies and by changes in the interfacial energy. For copper nanocrystals supported on silica, the support has negligible influence on the structure. Nanoparticle dynamics must be included in the description of catalytic and other properties of nanomaterials. In situ microscopy offers possibilities for obtaining the relevant atomic-scale insight.read more
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Dynamic adsorbate/reaction induced structural change of supported metal nanoparticles: heterogeneous catalysis and beyond
TL;DR: The aim of this tutorial review is to discuss how the authors might observe and categorise differing types of dynamic change, and to give some specific examples of where and how this fundamental structural dynamism can be tangibly linked to the reactive behaviour of heterogeneous catalysts.
Journal ArticleDOI
Environmental electron microscopy (ETEM) for catalysts with a closed E-cell with carbon windows.
TL;DR: For the first time, Au and Pd clusters supported on TiO(2) and amorphous carbon have been observed with a windows-cell environmental electron microscopy (ETEM) system, with the resolution of the (1 1 1) lattice fringes.
Journal ArticleDOI
Crystal-plane-controlled surface restructuring and catalytic performance of oxide nanocrystals.
TL;DR: It is crucial to explore the restructuring process of catalyst surfaces under reaction conditions to understand catalytic processes at the microscopic level and desirable to tune the catalytic performance of the catalyst nanoparticles by con-trolling the surface restructuring process in reactive atmos-pheres.
Journal ArticleDOI
Sintering of nickel steam-reforming catalysts
TL;DR: In this paper, the effects of nickel loading, carrier surface area, and temperature on the nickel surface area were studied under simulated industrial conditions, i.e., in a mixture of steam and hydrogen (10:1) in the temperature range of 500 −682 ÂC and at 30 bar total pressure.
Reference EntryDOI
Particle Size and Dispersion Measurements
Gérard Bergeret,Pierre Gallezot +1 more
TL;DR: The relationship between Particle size, surface area, and dispersal is discussed in this article, where the authors propose a method to measure the nuclearity of a particle by gas chemisorption.
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Controlled growth of monodisperse silica spheres in the micron size range
TL;DR: In this article, a system of chemical reactions has been developed which permits the controlled growth of spherical silica particles of uniform size by means of hydrolysis of alkyl silicates and subsequent condensation of silicic acid in alcoholic solutions.
Journal ArticleDOI
Semiconductor Clusters, Nanocrystals, and Quantum Dots
TL;DR: In this article, the authors focus on the properties of quantum dots and their ability to join the dots into complex assemblies creates many opportunities for scientific discovery, such as the ability of joining the dots to complex assemblies.
Reference BookDOI
Handbook of Heterogeneous Catalysis
TL;DR: This paper presents a meta-modelling system that automates the very labor-intensive and therefore time-heavy and therefore expensive and expensive process of characterization and activation of Solid Catalysts.
Journal ArticleDOI
Photoinduced conversion of silver nanospheres to nanoprisms.
TL;DR: This light-driven process results in a colloid with distinctive optical properties that directly relate to the nanoprism shape of the particles, which could be useful in developing multicolor diagnostic labels on the basis of nanoparticle composition and size but also of shape.
Journal ArticleDOI
Some interesting properties of metals confined in time and nanometer space of different shapes.
TL;DR: Some of the observed new chemical, optical, and thermal properties of metallic nanocrystals when their size is confined to the nanometer length scale and their dynamical processes are observed on the femto- to picosecond time scale are described.