Dynamic and Structural Characteristics of Heterogeneous Catalysts at the Atomic Scale

September 16, 2016

Phil Christopher

The use of heterogeneous catalysts for important chemical conversions ranging from pollution mitigation to energy production relies on the design of active catalytic sites consisting of metal nanoparticles supported on high surface area oxide materials.  Key to design of these systems is the identification of active site geometries and compositions that are optimized for desired catalytic reactions. These active sites vary in structural diversity from single metal atoms on oxide supports to unique interfaces between faceted metal nanoparticles and oxide supports, making their characterization complex. This difficulty is further complicated because the exposure of oxide-supported metals to reactive environments can induce significant transformations in the structure of the metal, support, and interactions between the metal and support. The dynamic transformations in catalytic structures induced by exposure to reactions can cause significant changes in the reactivity of the structures, requiring detailed in-situ analysis to identify active site motifs. I will highlight a few examples where we exploit quantitative and in-situ spectroscopy and microscopy to characterize heterogeneous catalysts at atomic scale and identify how reactive conditions modify active site structures and relate this to catalytic performance.