(415l) Strain Effects on Oxygen Binding and Phase Change on Pd Surfaces

Methane is a high energy-per-carbon fuel that can aid in the production of energy while meeting emissions targets in the short term, but it is also a potent greenhouse gas. Catalytic combustion over Pd-based catalysts under oxidizing conditions is an attractive option to prevent the emission of uncombusted methane by completely oxidizing methane to CO₂. Our recent work¹ has shown that the presence of twin boundaries in Pd nanoparticles increases the methane activation activity, and strain at the vicinity of these twin boundaries may lead to the observed increase in methane oxidation rates. In this talk, the facet-dependent behavior of strain effects on oxygen binding strength to Pd surfaces is explored. We establish that expansive strain on the close-packed Pd(111) surface leads to stronger binding of oxygen, while more open facets like the Pd(100) facet do not exhibit the same behavior. Strain-dependent phase diagrams are then presented for O* coverage and PdO formation on top of the Pd(100) facet. From these diagrams, we establish how strain can influence the preferred PdO facet presented when supported on the Pd(100) facet. These results build upon the understanding of how strain can influence the rate of methane combustion and can help guide future efforts to design improved methane combustion catalysts.

1. Huang, W., Johnston-Peck, A. C., Wolter, T., Yang, W. C. D., Xu, L., Oh, J., Reeves, B. A., Zhou, C., Holtz, M. E., Herzing, A. A., Lindenberg, A. M., Mavrikakis, M. & Cargnello, M. Science 373, 1518–1523 (2021).