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Author |
Liu, P.; Madsen, J.; Schiotz, J.; Wagner, J.B.; Hansen, T.W. |
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Title |
Reversible and concerted atom diffusion on supported gold nanoparticles |
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A1 Journal article |
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Year  |
2020 |
Publication |
Journal Of Physics-materials |
Abbreviated Journal |
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Volume |
3 |
Issue |
2 |
Pages |
024009 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Traditionally, direct imaging of atom diffusion is only available by scanning tunneling microscopy and field ion microscopy on geometry-constrained samples: flat surfaces for STM and needle tips for FIM. Here we show time-resolved atomic-scale HRTEM investigations of CeO2-supported Au nanoparticle surfaces to characterize the surface dynamics of atom columns on gold nanoparticles. The observed surface dynamics have been categorized into four types: layer jumping, layer gliding, re-orientation and surface reconstruction. We successfully captured atoms moving in a concerted manner with a time resolution of 0.1 s. A quantitative approach for measuring the dynamics in various gaseous surroundings at elevated temperatures is presented. An approach for measuring quantitative electron beam effects on the surface dynamics is presented by counting atom column occupation as a function of time under a range of dose rates in high vacuum. |
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Wos |
000560432800009 |
Publication Date |
2020-03-24 |
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UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
2 |
Open Access |
OpenAccess |
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Notes |
; ; |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:171320 |
Serial |
6597 |
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Author |
Liu, P.; Wu, T.; Madsen, J.; Schiotz, J.; Wagner, J.B.; Hansen, T.W. |
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Title |
Transformations of supported gold nanoparticles observed by in situ electron microscopy |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
Nanoscale |
Abbreviated Journal |
Nanoscale |
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Volume |
11 |
Issue |
24 |
Pages |
11885-11891 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Oxide supported metal nanoparticles play an important role in heterogeneous catalysis. However, understanding the metal/oxide interface and their evolution under reaction conditions remains challenging. Herein, we investigate the interface between Au nanoparticles and a CeO2 substrate by environmental transmission electron microscopy with atomic resolution. We find that the Au nanoparticles have two preferential epitaxial relationships with the substrate, i.e. Type I (111)[-110]CeO2//(111)[-110]Au and Type II (111)[-110]CeO2//(111)[1-10]Au orientation relationships, where Type I is preferred. In situ observations in the presence of O-2 show that the gas can stimulate the supported Au nanoparticles to transform between these two orientations even at room temperature. Moreover, when increasing the temperature to 973 K, the transformation of an Au nanoparticle between the two orientation states and a non-crystalline state in the presence of O-2 is also observed. DFT calculations of the binding between Au and CeO2 in the two relationships are strongly influenced by the presence of oxygen vacancies. For a given position of a vacancy, there is a significant energy difference between the energy of the two types. However, for some positions, Type I is preferred, and for others, Type II, but the most favourable position of the vacancy for the two types has a very similar energy. This is consistent with the observation of both types of adhesion. |
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Wos |
000472559800049 |
Publication Date |
2019-05-22 |
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ISSN |
2040-3364 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
7.367 |
Times cited |
1 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 7.367 |
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Call Number |
UA @ admin @ c:irua:161313 |
Serial |
5402 |
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