Atomic-Scale Understanding of Gold Cluster Growth on Different Substrates and Adsorption-Induced Structural Change

Abstract

To fully understand the properties of functional nanocatalysts including nanoclusters and nanoparticles, it is necessary to know the geometric and electronic structures of the nanostructure. The catalytic properties of noble metal nanoclusters can often be improved by the formation of heterostructures on different support, but little is known about their atomic-scale structures and their interaction with the support materials. Here, we report the size-and support-dependent structures for Au nanoclusters by combining aberrationcorrected scanning transmission electron microscopy and density functional theory calculations. We demonstrate lattice-induced epitaxial coherence growth for Au nanoclusters on crystalline substrate of (110) MgO, different from the chainlike or random structures on amorphous carbon support. The time sequential atomic scale observations confirm that Au clusters tend to easily migrate on crystalline MgO support. DFT calculations based on the experiment results imply the CO adsorption on MgO supported Au clusters prefer to bind at apex sites, and the adsorption can induce the 3D structural change of the supported nanoclusters, resulting in the formation of linear and bridge CO species. The results should help to clarify the atomistic origin of shape-, number-, and support-dependent catalytic activity in the supported Au clusters catalysts.

Large-Scale Fabrication of Hollow Pt3Al Nanoboxes and Their Electrocatalytic Performance for Hydrogen Evolution Reaction

“…The specimen was further investigated in the HAADF-STEM mode (Figure d–f). Due to the intensity of each atomic column in HAADF-STEM image (where the intensity is directly proportional to Z ∼1.7 ( Z : atomic number)), the atom columns can be identified directly based on atomic models. − The high-resolution HAADF-STEM image in the marked region in Figure f matches well with the atomic models of Pt 3 Al along [11̅0] direction (Figure S3, Supporting Information), which corroborates the tetragonal structure of the formed Pt 3 Al nanocrystals. To show the hollow structure more clearly, we analyzed the change of intensity along with an individual hollow nanoparticle in HAADF-STEM image, as shown in Figure S4, where the hollow interior is found to be ca.…”

Ultrafine-Grained Porous Ir-Based Catalysts for High-Performance Overall Water Splitting in Acidic Media

“…The specimen was further investigated in high-angle annular-dark-field STEM mode (HAADF-STEM, Figure i–k). Since the intensity of an atomic column in HAADF-STEM imaging mode is directly proportional to Z 1.7 ( Z : atomic number), the atom columns can be identified on the basis of the atomic model. − The atomic-resolution HAADF-STEM images in the regions marked in Figure j,k match well with the atomic models of IrO 2 viewed along the [001] (Figure l) and [010] (Figure S5c) directions, respectively, which confirms the tetragonal structure of the formed IrO 2 nanocrystals. The chemical composition of np -IrO 2 was further examined by EDS mapping (Figure m–p) and the EDS spectrum (Figure S6), verifying that np -IrO 2 is composed exclusively of Ir and O and Al was completely leached out during the electrochemical activation.…”

Electronic Detection of Oxygen Adsorption and Size‐Specific Doping of Few‐Atom Gold Clusters on Graphene

“…The size‐dependent characteristics can be preserved in the interaction of a cluster with a support. For specific gold, cobalt and germanium clusters, dedicated atomic resolution surface probe studies, using scanning tunneling microscopy and scanning transmission electron microscopy, have, in combination with density functional theory (DFT) simulations, allowed for a detailed morphological characterization of clusters on supports. The overall properties of a cluster‐support system retain a dependence on the exact cluster size .…”