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

2013 ◽  
Vol 4 (14) ◽  
pp. 2256-2263 ◽  
Author(s):  
Prasenjit Ghosh ◽  
Matteo Farnesi Camellone ◽  
Stefano Fabris
Keyword(s):  
Co Oxidation ◽  
Surface Defects ◽  
Au Clusters ◽  
Dft Simulations

Mechanistic interpretation of CO oxidation turnover rates on supported Au clusters

2012 ◽  
Vol 285 (1) ◽  
pp. 92-102 ◽  
Author(s):  
Manuel Ojeda ◽  
Bi-Zeng Zhan ◽  
Enrique Iglesia
Keyword(s):  
Co Oxidation ◽  
Turnover Rates ◽  
Au Clusters

scholarly journals Size-dependent dynamic structures of supported gold nanoparticles in CO oxidation reaction condition

2018 ◽  
Vol 115 (30) ◽  
pp. 7700-7705 ◽  
Author(s):  
Yang He ◽  
Jin-Cheng Liu ◽  
Langli Luo ◽  
Yang-Gang Wang ◽  
Junfa Zhu ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Oxidation Reaction ◽  
Au Nanoparticles ◽  
Working Condition ◽  
Ab Initio Molecular Dynamics ◽  
Present Observation ◽  
Size Dependent ◽  
Reaction Condition ◽  
Au Clusters ◽  
Co Oxidation Reaction

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.

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

Nano Letters ◽  
2012 ◽  
Vol 12 (7) ◽  
pp. 3621-3626 ◽  
Author(s):  
Michail Stamatakis ◽  
Matthew A. Christiansen ◽  
Dionisios G. Vlachos ◽  
Giannis Mpourmpakis
Keyword(s):  
Co Oxidation ◽  
Multiscale Modeling ◽  
Au Clusters

STM Study of Au Adsorption on Si(111)-7 × 7 Surface: Voltage and Temperature Dependence

2008 ◽  
Vol 8 (6) ◽  
pp. 3030-3035 ◽  
Author(s):  
Yinghui Zhou ◽  
Qi-Hui Wu ◽  
Junyong Kang
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Temperature Dependence ◽  
Surface Defects ◽  
Scanning Tunneling ◽  
Si Substrate ◽  
Tunneling Microscopy ◽  
Au Clusters ◽  
Voltage Dependent ◽  
Reconstructed Surface

We presented the scanning tunneling microscopy (STM) results on the study of Au adsorption at Si(111)-7 × 7 reconstructed surface. The voltage-dependent STM measurements indicated that there are at least three kinds of Au clusters and two types of single Au atoms adsorption on Si(111)-7 × 7 surface with Au coverage of about 0.2 monolayer. After the Au adsorbed Si surface was annealed at about 250 °C, the adsorbed Au clusters would diffuse into the Si substrate, and consequently create surface defects on the Si substrate. Sequentially annealed the sample at about 500 °C, the diffused Au would emerge out again and form larger 3-dimension Au clusters at the Si surface.

C, N co-doping promoted mesoporous Au/TiO2 catalyst for low temperature CO oxidation

RSC Advances ◽  
2016 ◽  
Vol 6 (34) ◽  
pp. 28904-28911 ◽  
Author(s):  
Liang Li ◽  
Binghan Wu ◽  
Gengnan Li ◽  
Yongsheng Li
Keyword(s):  
Low Temperature ◽  
Co Oxidation ◽  
Surface Defects ◽  
Catalytic Activities ◽  
Co Doping ◽  
Support Interaction ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Low Temperature Co Oxidation ◽  
C And N

The doping of C and N into meso-structured TiO2 increases the number of surface defects which could improve the absorption of oxygen, tune the metal-support interaction and promote the catalytic activities for CO oxidation.

scholarly journals Surface Defects as Ingredients That Can Improve or Inhibit the Pathways for CO Oxidation at Low Overpotentials Using Pt(111)-Type Catalysts

2020 ◽  
Vol 124 (49) ◽  
pp. 26583-26595
Author(s):  
Manuel J. S. Farias ◽  
Adilson L. P. Silva ◽  
Auro A. Tanaka ◽  
Enrique Herrero ◽  
Juan M. Feliu
Keyword(s):  
Co Oxidation ◽  
Surface Defects

scholarly journals Investigations of the Effect of H2 in CO Oxidation over Ceria Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1556
Author(s):  
Arantxa Davó-Quiñonero ◽  
Sergio López-Rodríguez ◽  
Cristian Chaparro-Garnica ◽  
Iris Martín-García ◽  
Esther Bailón-García ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Surface Defects ◽  
Co Adsorption ◽  
Oxidation Mechanism ◽  
Density Functional Theory Calculations ◽  
Hydroxyl Groups ◽  
Selective Co Oxidation ◽  
Physicochemical Features

The preferential CO oxidation (so-called CO-PROX) is the selective CO oxidation amid H2-rich atmospheres, a process where ceria-based materials are consolidated catalysts. This article aims to disentangle the potential CO–H2 synergism under CO-PROX conditions on the low-index ceria surfaces (111), (110) and (100). Polycrystalline ceria, nanorods and ceria nanocubes were prepared to assess the physicochemical features of the targeted surfaces. Diffuse reflectance infrared Fourier-transformed spectroscopy (DRIFTS) shows that ceria surfaces are strongly carbonated even at room temperature by the effect of CO, with their depletion related to the CO oxidation onset. Conversely, formate species formed upon OH + CO interaction appear at temperatures around 60 °C and remain adsorbed regardless the reaction degree, indicating that these species do not take part in the CO oxidation. Density functional theory calculations (DFT) reveal that ceria facets exhibit high OH coverages all along the CO-PROX reaction, whilst CO is only chemisorbed on the (110) termination. A CO oxidation mechanism that explains the early formation of carbonates on ceria and the effect of the OH coverage in the overall catalytic cycle is proposed. In short, hydroxyl groups induce surface defects on ceria that increase the COx–catalyst interaction, revealed by the CO adsorption energies and the stabilization of intermediates and readsorbed products. In addition, high OH coverages are shown to facilitate the hydrogen transfer to form less stable HCOx products, which, in the case of the (110) and (100), is key to prevent surface poisoning. Altogether, this work sheds light on the yet unclear CO–H2 interactions on ceria surfaces during CO-PROX reaction, providing valuable insights to guide the design of more efficient reactors and catalysts for this process.

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

2015 ◽  
Vol 5 (1) ◽  
pp. 134-141 ◽  
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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