I will show that dynamic catalytic interfaces exhibit a great structural fluxionality in conditions of catalysis, and thus need to be viewed (and modeled) as dynamic ensembles of many states. This leads to beautiful and bewildering properties of such interfaces. Multitude of metastable states dictates the catalytic activity, selectivity, and durability. Every intermediate of the catalyzed reaction is bound to a different ensemble-state of the catalyst. For every step of the reaction, the most stable catalyst isomer may not be the most catalytically active, and thus thermodynamics and kinetics are governed by different states of the catalyst. This then leads to an inescapable break-down of scaling relations, which normally preclude catalyst optimization beyond a certain fundamental limit. Phase diagrams of dynamic catalytic interfaces define phases as ensembles of many states of different structures and also stoichiometries. This new paradigm of dynamic catalytic interfaces will be illustrated using several catalytic systems: semiconductor surfaces decorated with small Pt clusters used for selective hydrocarbon dehydrogenation, Pt clusters on graphene used for oxygen reduction reaction, diamond-supported Cu and Pd clusters and also hexagonal boron nitride used for selective oxidative dehydrogenation. Most of this work is done in close collaboration with experiment, particularly <i>operando</i> spectroscopy when possible.

Dynamic catalytic interfaces: Ensembles of multiple metastable states break the rules of catalysis

2019 Fall National Meeting

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