(788c) Seeing Where Catalysis Occurs Through High-Resolution TEM Imaging

Direct observation of catalytically active sites is critical to understanding the effects of local site structure and composition on catalyst activity and selectivity. Advances in high-resolution TEM and STEM have opened the way for observing the structure of catalysts with atomic spatial and elemental resolution. As a result it has now become possible to identify individual sites at which catalysis occurs, the role of edges and defects, and the location of catalyst promoters. Further advances have been achieved in the design of cells for in situ observations of catalyst. This talk will illustrate the application of advanced electron microscopy techniques for observing the growth and morphology of graphene layers formed on Pt and PtSn nanoparticles and the distribution of Mn on the surface of Co particles. The challenges to making in situ observations of catalysts will also be discussed. These include attainment of relevant temperatures and pressures and minimization of the effects of electron beam on the location and geometry of the catalyst particles observed and on beam-induced chemistry.