Three-Dimensional Structural Analysis of MgO-Supported Osmium Clusters by Electron Microscopy with Single-Atom Sensitivity

摘要

Supported metals are a widely applied class of industrial catalyst with properties depending on the size, shape, and structure of the metal species. The sensitivity of the catalytic properties to the structure is maximized when the structures are smallest and the interactions of the metal with the support maximized. Consequently, attention has increasingly been focused on metal species in the size range between single-metal-atom (mononuclear) metal complexes and clusters that incorporate less than about 10 metal atoms. Work on such catalysts is now emerging from industrial laboratories, especially those concerned with supported platinum for hydrocarbon conversions. Understanding of the properties of such highly dispersed metals is benefiting especially from the application of atomic-resolution scanning transmission electron microscopy (STEM). Recent reports, including those from industry, illustrate the power of this technique, especially when used in concert with spectroscopic methods. Important next steps are determination of the nuclearities and three-dimensional structures of supported metal clusters present in mixtures typical of industrial catalysts.