Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Theoretical Study of Ripening Mechanisms of Pd Clusters on Ceria.

ABSTRACT: We carried out density functional theory calculations to investigate the ripening of Pd clusters on CeO2(111). Starting from stable Pd n clusters (n = 1-21), we compared how these clusters can grow through Ostwald ripening and coalescence. As Pd atoms have mobility higher than that of Pd n clusters on the CeO2(111) surface, Ostwald ripening is predicted to be the dominant sintering mechanism. Particle coalescence is possible only for clusters with less than 5 Pd atoms. These ripening mechanisms are facilitated by adsorbed CO through lowering barriers for the cluster diffusion, detachment of a Pd atom from clusters, and transformation of initial planar clusters.

SUBMITTER: Su YQ

PROVIDER: S-EPMC5695895 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Theoretical Study of Ripening Mechanisms of Pd Clusters on Ceria.

Su Ya-Qiong YQ Liu Jin-Xun JX Filot Ivo A W IAW Hensen Emiel J M EJM

Chemistry of materials : a publication of the American Chemical Society 20171013 21

We carried out density functional theory calculations to investigate the ripening of Pd clusters on CeO2(111). Starting from stable Pd n clusters (n = 1-21), we compared how these clusters can grow through Ostwald ripening and coalescence. As Pd atoms have mobility higher than that of Pd n clusters on the CeO2(111) surface, Ostwald ripening is predicted to be the dominant sintering mechanism. Particle coalescence is possible only f ...[more]

PMID: 29170602

Similar Datasets

Ostwald ripening of clusters during protein crystallization.

Project description:Contrary to classical nucleation theory, protein crystals can nucleate via a two-step process in which the molecular arrangement of the ordered solid phase is preceded by nucleation of a dense amorphous phase. We study the growth of these precrystalline clusters in lysozyme using a combination of dynamic light scattering, optical microscopy, and microfluidics. Clusters display Ostwald ripening growth kinetics but deviate from this trend after nucleation of the crystal phase. This behavior arises from the metastable relationship between clusters and the ordered solid and is explained numerically using a population balance model.

| S-EPMC4141884 | biostudies-literature

A role for [Fe4S4] clusters in tRNA recognition--a theoretical study.

Project description:Over the past several years, structural studies have led to the unexpected discovery of iron-sulfur clusters in enzymes that are involved in DNA replication/repair and protein biosynthesis. Although these clusters are generally well-studied cofactors, their significance in the new contexts often remains elusive. One fascinating example is a tryptophanyl-tRNA synthetase from the thermophilic bacterium Thermotoga maritima, TmTrpRS, that has recently been structurally characterized. It represents an unprecedented connection among a primordial iron-sulfur cofactor, RNA and protein biosynthesis. Here, a possible role of the [Fe4S4] cluster in tRNA anticodon-loop recognition is investigated by means of density functional theory and comparison with the structure of a human tryptophanyl-tRNA synthetase/tRNA complex. It turns out that a cluster-coordinating cysteine residue, R224, and polar main chain atoms form a characteristic structural motif for recognizing a putative 5' cytosine or 5' 2-thiocytosine moiety in the anticodon loop of the tRNA molecule. This motif provides not only affinity but also specificity by creating a structural and energetical penalty for the binding of other bases, such as uracil.

| S-EPMC4027196 | biostudies-literature

Stable Pd-Doped Ceria Structures for CH4 Activation and CO Oxidation.

Project description:Doping CeO2 with Pd atoms has been associated with catalytic CO oxidation, but current surface models do not allow CO adsorption. Here, we report a new structure of Pd-doped CeO2(111), in which Pd adopts a square planar configuration instead of the previously assumed octahedral configuration. Oxygen removal from this doped structure is favorable. The resulting defective Pd-doped CeO2 surface is active for CO oxidation and is also able to cleave the first C-H bond in methane. We show how the moderate CO adsorption energy and dynamic features of the Pd atom upon CO adsorption and CO oxidation contribute to a low-barrier catalytic cycle for CO oxidation. These structures, which are also observed for Ni and Pt, can lead to a more open coordination environment around the doped-transition-metal center. These thermally stable structures are relevant to the development of single-atom catalysts.

| S-EPMC5762167 | biostudies-literature

Reaction between Indazole and Pd-Bound Isocyanides-A Theoretical Mechanistic Study.

Project description:The mechanism of the addition of indazole (Ind)-a bifunctional aromatic N,NH-nucleophile-to cyclohexyl isocyanide coordinated to the palladium(II) center in the model complex cis-[PdCl₂(CNMe)(CNCy)] (1) to give the corresponding aminocarbene ligand was investigated in detail by theoretical (DFT) methods. The most plausible mechanism of this reaction is that of the associative type involving nucleophilic attack of Ind by its unprotonated N atom at the isocyanide carbon atom followed by the stepwise proton transfer from the nucleophile molecule to the isocyanide N atom via deprotonation/protonation steps. Two reaction channels based on two tautomeric forms of indazole were found. The channel leading to the experimentally isolated aminocarbene product is based on the less stable tautomeric form. Another channel based on the more stable tautomer of Ind is slightly kinetically more favorable but it is endergonic. Thus, the regioselectivity of this reaction is thermodynamically rather than kinetically driven. The bonding situation in key species was analyzed.

| S-EPMC6278333 | biostudies-literature

Spring-clusters study

Project description:Legionella and Legionella-hosts from natural saline spring-clusters

| PRJEB53014 | ENA

Theoretical Study of As?O? Adsorption Mechanisms on CaO surface.

Project description:Emission of hazardous trace elements, especially arsenic from fossil fuel combustion, have become a major concern. Under an oxidizing atmosphere, most of the arsenic converts to gaseous As?O?. CaO has been proven effective in capturing As?O?. In this study, the mechanisms of As?O? adsorption on CaO surface under O? atmosphere were investigated by density functional theory (DFT) calculation. Stable physisorption and chemisorption structures and related reaction paths are determined; arsenite (AsO?3-) is proven to be the form of adsorption products. Under the O? atmosphere, the adsorption product is arsenate (AsO?3-), while tricalcium orthoarsenate (Ca?As?O?) and dicalcium pyroarsenate (Ca?As?O?) are formed according to different adsorption structures.

| S-EPMC6416740 | biostudies-literature

Theoretical Study on Sandwich-Like Transition-Metal-Cyclooctatetraene Clusters and One-Dimensional Infinite Molecular Wires.

Project description:Using density functional theory calculations, we investigated the structure and electronic properties of cyclooctatetraene (C8H8, COT)-ligand mono- or bi-transition-metal (M) sandwich clusters, M n (COT) n+1 (M = Sc, Ti, Cr, Mn, n = 1, 2) or (COT)M1(COT)M2(COT), as well as their one-dimensional infinite molecular wires. All the sandwich M-COT clusters and molecular wires are rather stable with their binding energies ranging from 3.20 to 7.48 eV per transition-metal atom. Superior to M n Bz n+1 complexes, most sandwich M-COT complexes are in their high spin states with ultrahigh magnetic moments. Moreover, one-dimensional infinite molecular wires, [Cr(COT)]∞, [(COT)V(COT)Ti]∞ and [(COT)Sc(COT)Cr]∞, are predicted to be ferromagnetic half-metals. Our findings suggest that such M-COT sandwich complexes may be potential candidates for applications in spintronics.

| S-EPMC6648966 | biostudies-literature

Thermally Stable and Regenerable Platinum-Tin Clusters for Propane Dehydrogenation Prepared by Atom Trapping on Ceria.

Project description:Ceria (CeO2 ) supports are unique in their ability to trap ionic platinum (Pt), providing exceptional stability for isolated single atoms of Pt. The reactivity and stability of single-atom Pt species was explored for the industrially important light alkane dehydrogenation reaction. The single-atom Pt/CeO2 catalysts are stable during propane dehydrogenation, but are not selective for propylene. DFT calculations show strong adsorption of the olefin produced, leading to further unwanted reactions. In contrast, when tin (Sn) is added to CeO2 , the single-atom Pt catalyst undergoes an activation phase where it transforms into Pt-Sn clusters under reaction conditions. Formation of small Pt-Sn clusters allows the catalyst to achieve high selectivity towards propylene because of facile desorption of the product. The CeO2 -supported Pt-Sn clusters are very stable, even during extended reaction at 680 °C. Coke formation is almost completely suppressed by adding water vapor to the feed. Furthermore, upon oxidation the Pt-Sn clusters readily revert to the atomically dispersed species on CeO2 , making Pt-Sn/CeO2 a fully regenerable catalyst.

| S-EPMC5697674 | biostudies-literature

Unraveling the atomic structure, ripening behavior, and electronic structure of supported Au20 clusters.

Project description:The free-standing Au20 cluster has a unique tetrahedral shape and a large HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gap of around 1.8 electron volts. The "magic" Au20 has been intensively used as a model system for understanding the catalytic and optical properties of gold nanoclusters. However, direct real-space ground-state characterization at the atomic scale is still lacking, and obtaining fundamental information about the corresponding structural, electronic, and dynamical properties, is challenging. Here, using cluster-beam deposition and low-temperature scanning tunneling microscopy, atom-resolved topographic images and electronic spectra of supported Au20 clusters are obtained. We demonstrate that individual size-selected Au20 on ultrathin NaCl films maintains its pyramidal structure and large HOMO-LUMO gap. At higher cluster coverages, we find sintering of the clusters via Smoluchowski ripening to Au20n agglomerates. The evolution of the electron density of states deduced from the spectra reveals gap reduction with increasing agglomerate size.

| S-EPMC6941914 | biostudies-literature

Theoretical study of the structures of bimetallic Ag-Au and Cu-Au clusters up to 108 atoms.

Project description:The stable structures of Ag-Au and Cu-Au clusters with 1 : 1, 1 : 3 and 3 : 1 compositions with up to 108 atoms are obtained using a modified adaptive immune optimization algorithm with Gupta potential. The dominant motifs of Ag-Au and Cu-Au clusters are decahedron and icosahedron, respectively. However, in Ag-rich Ag-Au clusters, more icosahedra are found, and in Cu-rich Cu-Au clusters, there exist several decahedral motifs. Four Leary tetrahedral motifs are predicted. CucoreAushell configurations are predicted in Cu-Au clusters. In Ag-Au clusters, most Ag atoms are on the surface, but partial ones are located in the inner shell, while Au atoms are interconnected in the middle shell.

| S-EPMC6731704 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data