Toward Quantum Chemical Free Energy Simulations of Platinum Nanoparticles on Titania Support

Van Quan Vuong, Ka Hung Lee, Aditya A. Savara, Victor Fung, Stephan Irle

Research output: Contribution to journalArticlepeer-review

Abstract

Platinum nanoparticles (Pt-NPs) supported on titania surfaces are costly but indispensable heterogeneous catalysts because of their highly effective and selective catalytic properties. Therefore, it is vital to understand their physicochemical processes during catalysis to optimize their use and to further develop better catalysts. However, simulating these dynamic processes is challenging due to the need for a reliable quantum chemical method to describe chemical bond breaking and bond formation during the processes but, at the same time, fast enough to sample a large number of configurations required to compute the corresponding free energy surfaces. Density functional theory (DFT) is often used to explore Pt-NPs; nonetheless, it is usually limited to some minimum-energy reaction pathways on static potential energy surfaces because of its high computational cost. We report here a combination of the density functional tight binding (DFTB) method as a fast but reliable approximation to DFT, the steered molecular dynamics (SMD) technique, and the Jarzynski equality to construct free energy surfaces of the temperature-dependent diffusion and growth of platinum particles on a titania surface. In particular, we present the parametrization for Pt-X (X = Pt, Ti, or O) interactions in the framework of the second-order DFTB method, using a previous parametrization for titania as a basis. The optimized parameter set was used to simulate the surface diffusion of a single platinum atom (Pt1) and the growth of Pt6 from Pt5 and Pt1 on the rutile (110) surface at three different temperatures (T = 400, 600, 800 K). The free energy profile was constructed by using over a hundred SMD trajectories for each process. We found that increasing the temperature has a minimal effect on the formation free energy; nevertheless, it significantly reduces the free energy barrier of Pt atom migration on the TiO2 surface and the transition state (TS) of its deposition. In a concluding remark, the methodology opens the pathway to quantum chemical free energy simulations of Pt-NPs’ temperature-dependent growth and other transformation processes on the titania support.

Original languageEnglish
Pages (from-to)6471-6483
Number of pages13
JournalJournal of Chemical Theory and Computation
Volume19
Issue number18
DOIs
StatePublished - Sep 26 2023

Funding

The authors thank Gang Seob Jung (ORNL) and De-en Jiang (Vanderbilt University) for their helpful suggestions and discussions. The foundation of this manuscript is based on the contents of chapter 4 of Van-Quan Vuong’s PhD dissertation, titled “Development of Density-Functional Tight-Binding Methods for Chemical Energy Science,” which was submitted to the University of Tennessee in 2021.(43) V.Q.V and K.H.L. were supported by an Energy Science and Engineering Fellowship from the Bredesen Center for Interdisciplinary Research and Graduate Education at the University of Tennessee, Knoxville. This work was sponsored by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, Catalysis Science Program. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231, as well as cloud resources of the Compute and Data Environment for Science (CADES) at Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. The authors thank Gang Seob Jung (ORNL) and De-en Jiang (Vanderbilt University) for their helpful suggestions and discussions. The foundation of this manuscript is based on the contents of chapter 4 of Van-Quan Vuong’s PhD dissertation, titled “Development of Density-Functional Tight-Binding Methods for Chemical Energy Science,” which was submitted to the University of Tennessee in 2021. V.Q.V and K.H.L. were supported by an Energy Science and Engineering Fellowship from the Bredesen Center for Interdisciplinary Research and Graduate Education at the University of Tennessee, Knoxville. This work was sponsored by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, Catalysis Science Program. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231, as well as cloud resources of the Compute and Data Environment for Science (CADES) at Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. Notice of Copyright: This manuscript was authored by UT-Battelle, LLC under Contract DE-AC05–00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). Acknowledgments

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