Combining In-Situ Transmission Electron Microscopy and Infrared Spectroscopy for Understanding Dynamic and Atomic-Scale Features of Supported Metal Catalysts

The elucidation of structure-property relationships for supported metal catalysts requires atomic-scale descriptions and quantitative measurements of the relative population of various exposed active sites under reaction conditions. The requirement of describing catalyst structures under reaction conditions stems from the potential physical and chemical reconstruction that can be induced by changes in environment. Here we highlight our recent work, where catalyst characterization via a combination of in-situ transmission electron microscopy and infrared spectroscopy is used to provide sample averaged, site-specific atomic level information on supported metal catalysts under reaction conditions. We show two illustrative examples using different reaction systems: the oxidation of CO over supported Pt and the reduction of CO2 over supported Rh. Using these examples we demonstrate differentiation of the catalytic reactivity of small supported metal clusters from isolated atoms and interrogate the catalytic consequences of structural transformations such as adsorbate induced surface reconstruction of metal particles and adsorbate-mediated metal particle encapsulation by oxide supports. Insights gained from these techniques help elucidate structure-property relationships for these reactions including structure sensitivity and dynamic reactivity changes. We expect that this combination of characterization techniques will be generally useful for understanding structurally dynamic catalytic systems with atomic resolution.