presence of metastable sites<br/>We will show that sub-nano surface-supported catalytic clusters covered with adsorbates generally have many low-energy isomers accessible at elevated temperatures of catalysis. The most stable isomer may not be the most catalytically active. Additionally, isomers may interconvert with barriers of varying heights, in response to the environment, i.e. exhibit fluxionality, during catalysts. We model such catalysts as statistical ensembles in realistic conditions, using a number of novel methods.  We will show how practically-important properties of cluster catalysts, such as size-dependent activity, selectivity, and stability against deactivation can be correctly captured only within this statistical theoretical description. Side-by-side with the experiment, we demonstrate and explain the size-specific activities of Pt<sub>n</sub>/alumina toward alkene dehydrogenation, and the effect of nano-alloying with boron for reduced deactivation by coking. In these cases, the stationary older picture of a single cluster minimum completely fails to explain experiment.

Realities of cluster catalysts: Critical role of fluxionality, structural diversity in the ensemble, and presence of metastable sites

255th National Meeting (2018)

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