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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TLDR
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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Fabrication techniques and material properties of dielectric MgO thin films—A status review
TL;DR: In this article, the authors summarized the important research achievements on higher quality MgO thin films with novel physical properties and systematic interrelationship for fabrication conditions, crystal structure, composition predictions, surface morphology, electrical and optical characterizations.
Journal ArticleDOI
Enhanced wetting of Cu on ZnO by migration of subsurface oxygen vacancies.
TL;DR: It is revealed that the surface-directed migration of subsurface defects affects the Cu adhesion on polar ZnO(0001) in the technologically interesting temperature range up to 550 K, which implies that defect concentrations in the bulk are an important, and possibly controllable, parameter for the metal-on-oxide growth.
Journal ArticleDOI
CO Dissociation on Face-Centered Cubic and Hexagonal Close-Packed Nickel Catalysts: A First-Principles Study
Abstract: Exploring the dependence of the structure–activity relationship of catalysts is important for improving the activity and selectivity in heterogeneous catalysis. Among other factors, the influence of the crystal phases, face-centered cubic (FCC) and hexagonal close-packed (HCP), of Ni catalysts on CO dissociation is studied by density functional theory (DFT). Surface energies of numerous FCC and HCP facets are calculated to construct the corresponding morphologies, and the exposed facets (six facets for FCC Ni and five facets for HCP Ni) are used to investigate the CO dissociation. For FCC Ni, (311) is the most active facet with the least barrier of 1.58 eV, followed by (100) and (211) with barriers of 1.63 and 1.75 eV, respectively. For HCP Ni, (1012) is the most active facet with the least barrier of 1.73 eV, followed by (1011) with a barrier of 1.86 eV. On both FCC and HCP Ni, CO dissociation shows a dramatic structural sensitivity irrespective of direct or H-assisted pathway. Compared to the direct d...
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Influence of Adsorbates on the Electronic Structure, Bond Strain, and Thermal Properties of an Alumina-Supported Pt Catalyst
TL;DR: This work demonstrates that the metal-metal (M-M) bonding in these small clusters is responsive to the presence of adsorbates, exhibiting pronounced coverage-dependent strains in the clusters' M-M bonding, with concomitant modifications of their electronic structures.
Journal ArticleDOI
Real-time, in situ, atomic scale observation of soot oxidation
TL;DR: In this article, soot oxidation was observed at atomic scale in situ, in real-time, using a spherical aberration-corrected Environmental Transmission Electron Microscope (ETEM).
References
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Controlled growth of monodisperse silica spheres in the micron size range
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Semiconductor Clusters, Nanocrystals, and Quantum Dots
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