The importance of heterogeneous catalysis in modern applications is evident by estimates that place the value of the catalyst market at more than $16 billion.1 Computational methods are increasingly becoming crucial in gaining a fundamental understanding of the physicochemical phenomena resulting in catalytic activity. Such an understanding makes it possible to design improved catalysts; however, the complexity encountered in catalytic systems poses significant challenges in modelling them. For instance, catalytic materials expose a variety of inequivalent sites which typically have distinct chemical properties, and the neighboring environment of an elementary event may significantly affect its rate due to lateral interactions of the reactants with spectator adsorbates. We present an ab-initio kinetic Monte Carlo (KMC) framework that uses concepts from graph theory2 to overcome these challenges and easily treat complex chemistries and surface phenomena. This approach allows one to define elementary reaction events characterized by complex neighboring patterns of the sites involved. These sites can be of various types (such as steps or terraces) and occupied by monodentate, as well as multidentate species. Adsorbate-adsorbate lateral interactions are also treated in a generalized way by incorporating cluster expansions for the energetics and Brønsted-Evans-Polanyi relations to model the effect of coverage on activation barriers.3 We further showcase this approach by applying it to key catalytic reactions, in particular CO oxidation on Au nano-clusters,4 which is important for environmental and health reasons, and water-gas shift on single crystal Pt surfaces,5 which is relevant to H2 production from biomass. We show that our approach can provide a wealth of information, which can be used to explain experimental observations and obtain insight in the design of materials with desired catalytic properties. References 1 Fredonia, "World Catalysts", 2014, Industry Study 3217. 2 M. Stamatakis and D. G. Vlachos, Journal of Chemical Physics, 2011, 134, 214115. 3 J. Nielsen, M. d’Avezac, J. Hetherington and M. Stamatakis, Journal of Chemical Physics, 2013, 139, 224706. 4 M. Stamatakis, M. Christiansen, D. G. Vlachos and G. Mpourmpakis, Nano Letters, 2012, 12, 3621; N. Nikbin, N. Austin, D. G. Vlachos, M. Stamatakis and G. Mpourmpakis, Catalysis Science & Technology, 2015, 5: 134. 5 M. Stamatakis, Y. Chen and D. G. Vlachos, Journal of Physical Chemistry C, 2011, 115, 24750.

Unravelling the complexity of catalytic kinetics: Computational method development, applications, and perspective

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.