Dataset Information

Design Principles of Inert Substrates for Exploiting Gold Clusters' Intrinsic Catalytic Reactivity.

ABSTRACT: Ultralow stability of gold clusters prohibits the understanding of their intrinsic reactivity (that is vital for revealing the origin of gold's catalytic properties). Using density functional theory including many-body dispersion method, we aim to ascertain effective ways in exploiting gold clusters' intrinsic reactivity on carbon nanotubes (CNTs). We find that the many body van der Waals interactions are essential for gold clusters' reactivity on CNTs and even for O2 activation on these supported clusters. Furthermore, curvature and dopant of CNTs are found to qualitatively change the balance between physisorption and chemisorption for gold clusters on CNTs, determining the clusters' morphology, charge states, stability, and reactivity, which rationalize the experimental findings. Remarkably, N doped small curvature CNTs, which effectively stabilize gold clusters and retain their inherent geometric/electronic structures, can be promising candidates for exploiting gold clusters' intrinsic reactivity.

SUBMITTER: Gao W

PROVIDER: S-EPMC4602230 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Design Principles of Inert Substrates for Exploiting Gold Clusters' Intrinsic Catalytic Reactivity.

Gao Wang W Ting Cui Ting T Fu Zhu Yong Y Wen Zi Z Zhao Ming M Chen Li Jian J Jiang Qing Q

Scientific reports 20151013

Ultralow stability of gold clusters prohibits the understanding of their intrinsic reactivity (that is vital for revealing the origin of gold's catalytic properties). Using density functional theory including many-body dispersion method, we aim to ascertain effective ways in exploiting gold clusters' intrinsic reactivity on carbon nanotubes (CNTs). We find that the many body van der Waals interactions are essential for gold clusters' reactivity on CNTs and even for O2 activation on these support ...[more]

PMID: 26459871

Similar Datasets

Project description:Confining Au nanoparticles (NPs) in a restricted space (e.g., zeolite micropores) is a promising way of overcoming their inherent thermal instability and susceptibility to aggregation, which limit catalytic applications. However, such approaches involve complex, multistep encapsulation processes. Here, we describe a successful strategy and its guiding principles for confining small (<2 nm) and monodisperse Au NPs within commercially available beta and MFI zeolites, which can oxidize CO at 40 °C and show size-selective catalysis. This protocol involves post-synthetic modification of the zeolite internal surface with thiol groups, which confines AuCl x species inside microporous frameworks during the activation process whereby Au precursors are converted into Au nanoparticles. The resulting beta and MFI zeolites contain uniformly dispersed Au NPs throughout the void space, indicating that the intrinsic stability of the framework promotes resistance to sintering. By contrast, in situ scanning transmission electron microscopy (STEM) studies evidenced that Au precursors in bare zeolites migrate from the matrix to the external surface during activation, thereby forming large and poorly dispersed agglomerates. Furthermore, the resistance of confined Au NPs against sintering is likely relevant to the intrinsic stability of the framework, supported by extended X-ray absorption fine structure (EXAFS), H2 chemisorption, and CO Fourier transform infrared (FT-IR) studies. The Au NPs supported on commercial MFI maintain their uniform dispersity to a large extent after treatment at 700 °C that sinters Au clusters on mesoporous silicas or beta zeolites. Low-temperature CO oxidation and size-selective reactions highlight that most gold NPs are present inside the zeolite matrix with a diameter smaller than 2 nm. These findings illustrate how confinement favors small, uniquely stable, and monodisperse NPs, even for metals such as Au susceptible to cluster growth under conditions often required for catalytic use. Moreover, this strategy may be readily adapted to other zeolite frameworks that can be functionalized by thiol groups.

Project description:In this work we study isomers of several representative small clusters to find principles for their stability. Our conclusions about the principles underlying the structure of clusters are based on a huge database of 44 000 isomers generated for 58 different clusters on the density functional theory level by Minima Hopping. We explore the potential energy surface of small neutral, anionic and cationic isomers, moving left to right across the third period of the periodic table and varying the number of atoms n and the cluster charge state q (X q n , with X = {Na, Mg, Al, Si, Ge}, q = -1, 0, 1, 2). We use structural descriptors such as bond lengths and atomic coordination numbers, the surface to volume ratios and the shape factor as well as electronic descriptors such as shell filling and hardness to detect correlations with the stability of clusters. The isomers of metallic clusters are found to be structure seekers with a strong tendency to adopt compact shapes. However certain numbers of atoms can suppress the formation of nearly spherical metallic clusters. Small non-metallic clusters typically also do not adopt compact spherical shapes for their lowest energy structures. In both cases spherical jellium models are not any more applicable. Nevertheless for many structures, that frequently have a high degree of symmetry, the Kohn-Sham eigenvalues are bunched into shells and if the available electrons can completely fill such shells, a particularly stable structure can result. We call such a cluster whose shape gives rise to shells that can be completely filled by the number of available electrons an optimally matched cluster, since both the structure and the number of electrons must be special and match. In this way we can also explain the stability trends for covalent silicon and germanium cluster isomers, whose stability was previously explained by the presence of certain structural motifs. Thus we propose a unified framework to explain trends in the stability of isomers and to predict their structure for a wide range of small clusters.

Dataset Information

Design Principles of Inert Substrates for Exploiting Gold Clusters' Intrinsic Catalytic Reactivity.

Publications

Design Principles of Inert Substrates for Exploiting Gold Clusters' Intrinsic Catalytic Reactivity.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets