We will show that dynamic catalytic interfaces exhibit a great structural fluxionality in conditions of catalysis, and thus need to be modeled as ensembles of many states. The most stable isomers may not be the most catalytically active, and indeed often metastable states dictate the catalytic activity, selectivity, and durability. One example is sub-nano surface-supported catalytic clusters covered with adsorbates. We will show how all practically-important properties of cluster catalysts, such as size- and composition-dependent activity, selectivity, and stability against poisoning, can be correctly modeled (i.e. in agreement with experiment) only when the catalyst is considered to be a dynamical statistical ensemble. Additionally, states of the catalyst may rather easily interconvert with barriers of varying heights, in response to the changing adsorbates, and exhibit fluxionality during reaction steps. All these fundamental aspects are illustrated using oxidative and non-oxidative dehydrogenation on deposited clusters of Pt, Cu, and Pd as the focus reactions.

Dynamic catalytic interfaces: statistical ensembles of multiple metastable states dictate the properties

2019 Spring National Meeting

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