Atomic-Scale Mechanism of Platinum Catalyst Restructuring under a Pressure of Reactant Gas

Heterogeneous catalysis is key for chemical transformations. Understanding how catalysts' active sites dynamically evolve at the atomic scale under reaction conditions is a prerequisite for accurately determining catalytic mechanisms and predictably developing catalysts. We combine in situ timedependent scanning tunneling microscopy observations and machine-learning-accelerated first-principles 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 sub-nano-islands on the terraces, where under-coordinated sites are stabilized by the CO adsorbates. The fast and accurate machine-learning potential is key to enabling the exploration of tens of thousands of configurations for the COcovered restructuring catalyst. These studies open an avenue to achieve an atomic-scale understanding of the structural dynamics of more complex metal nanoparticle catalysts under reaction conditions.

Automated summary

It has been discovered that high CO coverage triggers the restructuring of Pt catalysts, forming atomic protrusions with low-coordination Pt atoms and sub-nano islands on the terraces. Machine-learning-accelerated first-principles atomistic simulations enable exploration of tens of thousands of configurations for CO-covered restructuring catalyst. These studies provide a new avenue for achieving atomic-scale understanding of the structural dynamics of more complex metal nanoparticle catalysts under reaction conditions.