Atomic scale mechanism of platinum catalyst restructuring under a pressure of reactant gas

Heterogeneous catalysis is key for chemical transformations. Understanding how catalyst active sites dynamically evolve at the atomic scale under reaction conditions is a prerequisite for accurate determination of catalytic mechanisms and predictably developing catalysts. We combine in-situ time-dependent observation and machine learning-accelerated first-principle atomistic simulations to uncover the mechanism of restructuring of Pt catalysts under a pressure of carbon monoxide (CO). We show that a high CO coverage at a Pt step edge triggers the formation of atomic protrusions of low-coordination Pt atoms, which then detach from the step edge to create subnano-islands on the terraces, where undercoordinated sites are stabilized by the CO adsorbates. The fast and accurate machine learning potential is key to enable the exploration of ten of thousands of configurations for the CO covered restructuring catalyst. These studies open an avenue to achieve atom-scale understanding of structural dynamics of more complex metal nanoparticle catalysts under reaction.