Mechanistic interpretation of CO oxidation turnover rates on supported Au clusters

Gold (Au) catalysts exhibit a significant size effect, but its origin has been puzzling for a long time. It is generally believed that supported Au clusters are more or less rigid in working condition, which inevitably leads to the general speculation that the active sites are immobile. Here, by using atomic resolution in situ environmental transmission electron microscopy, we report size-dependent structure dynamics of single Au nanoparticles on ceria (CeO2) in CO oxidation reaction condition at room temperature. While large Au nanoparticles remain rigid in the catalytic working condition, ultrasmall Au clusters lose their intrinsic structures and become disordered, featuring vigorous structural rearrangements and formation of dynamic low-coordinated atoms on surface. Ab initio molecular-dynamics simulations reveal that the interaction between ultrasmall Au cluster and CO molecules leads to the dynamic structural responses, demonstrating that the shape of the catalytic particle under the working condition may totally differ from the shape under the static condition. The present observation provides insight on the origin of superior catalytic properties of ultrasmall gold clusters.

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Multiscale Modeling Reveals Poisoning Mechanisms of MgO-Supported Au Clusters in CO Oxidation

Nano Letters ◽

10.1021/nl301318b ◽

2012 ◽

Vol 12 (7) ◽

pp. 3621-3626 ◽

Cited By ~ 45

Author(s):

Michail Stamatakis ◽

Matthew A. Christiansen ◽

Dionisios G. Vlachos ◽

Giannis Mpourmpakis

Keyword(s):

Co Oxidation ◽

Multiscale Modeling ◽

Au Clusters

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Catalytic activity of small MgO-supported Au clusters towards CO oxidation: A density functional study

Physical Review B ◽

10.1103/physrevb.81.195443 ◽

2010 ◽

Vol 81 (19) ◽

Cited By ~ 33

Author(s):

Martin Amft ◽

Natalia V. Skorodumova

Keyword(s):

Catalytic Activity ◽

Co Oxidation ◽

Density Functional ◽

Functional Study ◽

Density Functional Study ◽

Au Clusters

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Catalysis at the sub-nanoscale: complex CO oxidation chemistry on a few Au atoms

Catalysis Science & Technology ◽

10.1039/c4cy01295j ◽

2015 ◽

Vol 5 (1) ◽

pp. 134-141 ◽

Cited By ~ 21

Author(s):

Nima Nikbin ◽

Natalie Austin ◽

Dionisios G. Vlachos ◽

Michail Stamatakis ◽

Giannis Mpourmpakis

Keyword(s):

Co Oxidation ◽

Magic Number ◽

Multiscale Simulations ◽

Catalytic Behavior ◽

Au Clusters ◽

Oxidation Chemistry

Multiscale simulations elucidate the experimentally observed “magic number” CO oxidation catalytic behavior of sub-nanoscale Au clusters.

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Fluxionality of Au Clusters at Ceria Surfaces during CO Oxidation: Relationships among Reactivity, Size, Cohesion, and Surface Defects from DFT Simulations

The Journal of Physical Chemistry Letters ◽

10.1021/jz4009079 ◽

2013 ◽

Vol 4 (14) ◽

pp. 2256-2263 ◽

Cited By ~ 61

Author(s):

Prasenjit Ghosh ◽

Matteo Farnesi Camellone ◽

Stefano Fabris

Keyword(s):

Co Oxidation ◽

Surface Defects ◽

Au Clusters ◽

Dft Simulations

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Colloidal systems in soils

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168050 ◽

1994 ◽

Vol 52 ◽

pp. 64-65

Author(s):

J. Thieme ◽

J. Niemeyer ◽

P. Guttman

Keyword(s):

Clay Minerals ◽

Polymeric Materials ◽

Spatial Arrangement ◽

High Specific Surface Area ◽

Turnover Rates ◽

Colloidal Systems ◽

Chemical Conditions ◽

Aggregation Phenomena ◽

Iron And Manganese ◽

Soil Colloids

In soil science the fraction of colloids in soils is understood as particles with diameters smaller than 2μm. Clay minerals, aquoxides of iron and manganese, humic substances, and other polymeric materials are found in this fraction. The spatial arrangement (microstructure) is controlled by the substantial structure of the colloids, by the chemical composition of the soil solution, and by thesoil biota. This microstructure determines among other things the diffusive mass flow within the soils and as a result the availability of substances for chemical and microbiological reactions. The turnover of nutrients, the adsorption of toxicants and the weathering of soil clay minerals are examples of these surface mediated reactions. Due to their high specific surface area, the soil colloids are the most reactive species in this respect. Under the chemical conditions in soils, these minerals are associated in larger aggregates. The accessibility of reactive sites for these reactions on the surface of the colloids is reduced by this aggregation. To determine the turnover rates of chemicals within these aggregates it is highly desirable to visualize directly these aggregation phenomena.

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Catalytic CO Oxidation on Unreconstructed Cu(110) by Reactive As-Adsorbed Oxygen Atoms below 230 K

The Journal of Physical Chemistry ◽

10.1021/jp952175e ◽

1996 ◽

Vol 100 (3) ◽

pp. 1048-1054 ◽

Cited By ~ 5

Author(s):

Tsuyoshi Sueyoshi ◽

Takehiko Sasaki ◽

Yasuhiro Iwasawa

Keyword(s):

Co Oxidation ◽

Adsorbed Oxygen ◽

Catalytic Co Oxidation ◽

Oxygen Atoms

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Turnover and Distribution of 131Iodine-Labelled Human Fibrinogen

Thrombosis and Haemostasis ◽

10.1055/s-0038-1654837 ◽

1964 ◽

Vol 11 (02) ◽

pp. 404-422 ◽

Cited By ~ 10

Author(s):

Annemarie Amris ◽

C. J Amris

Keyword(s):

Body Weight ◽

Cancer Patient ◽

Distribution Ratio ◽

Half Life ◽

Fibrinolytic Activity ◽

The Other ◽

Turnover Rates ◽

Human Fibrinogen ◽

Coagulation Defects ◽

Fractional Turnover

Summary14 patients (5 diabetics with arteriosclerotic complications, 4 patients with thrombo-embolic disease, 4 with cirrhosis, coagulation defects and increased fibrinolytic activity, and 1 cancer patient) and 3 control patients were subjected to turnover studies with 13iodine labelled human fibrinogen.Half-life times in the control patients were found to be 4 days, the fractional turnover rates 19–23 per cent, of intravascular fibrinogen per day, and the absolute turnover 0.02 to 0.06 gm per day per kg. body weight. The other patient’s half-life times and turnover rates varied considerably from 0.9–5.5 days, 13–160 per cent, per day of intravascular fibrinogen and 0.02–0.4 gm per day per kg. body weight respectively.As fibrinogen unlike other proteins subjected to turnover studies, is converted to fibrin, it is not possible to measure the true intra-extravascular distribution ratio of fibrinogen. But intravascular fibrinogen could be approximated to constitute 68–99 per cent, of the total fibrinogen. There is justification in believing that fibrinogen is degradated through a continuous coagulation in equilibrium with fibrinolysis, and that the organism contains a greater mass of fibrin, the “fibrin pool”. Considerations of the turnover mechanism can however only be hypothetical.

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