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Automated Detection and Characterization of Surface Restructuring Events in Bimetallic Catalysts

preprint
submitted on 10.04.2019 and posted on 11.04.2019 by Jin Soo Lim, Nicola Molinari, Kaining Duanmu, Philippe Sautet, Boris Kozinsky
Surface restructuring in bimetallic systems has recently been shown to play a crucial role in heterogeneous catalysis. In particular, the segregation in binary alloys can be reversed in the presence of strongly bound adsorbates. Mechanistic characterization of such restructuring phenomena at the atomic level remains scarce and challenging due to the large configurational space that must be explored. To this end, we propose an automated method to discover elementary surface restructuring processes in an unbiased fashion, using Pd/Ag as an example. We employ high-temperature classical molecular dynamics (MD) to rapidly detect restructuring events, isolate them, and optimize using density functional theory (DFT). In addition to confirming the known exchange descent mechanism, our systematic approach has revealed three new predominant classes of events at step edges of close-packed surfaces that have not been considered before: (1) vacancy insertion; (2) direct exchange; (3) interlayer exchange. The discovered events enable us to construct the complete set of mechanistic pathways by which Pd is incorporated into the Ag host in vacuum. These atomistic insights provide a step toward systematic understanding and engineering of surface segregation dynamics in bimetallic catalysts.

Funding

Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC)

Basic Energy Sciences

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History

Email Address of Submitting Author

nmolinari@seas.harvard.edu

Institution

Harvard University

Country

United States of America

ORCID For Submitting Author

0000-0002-2913-7030

Declaration of Conflict of Interest

We declare no conflict of interests.

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