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Ab Initio Molecular Dynamics Reveals New Metal-Binding Sites in Atomically Dispersed Pt1/TiO2 Catalysts

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journal contribution
posted on 23.10.2020, 14:15 by Nicholas Humphrey, Selin Bac, Shaama Mallikarjun Sharada
We present a molecular dynamics modeling study of atomically dispersed Pt on the (110) surface of rutile TiO2. Using density functional theory (DFT) and ab initio molecular dynamics (AIMD), we probe the dynamic evolution of the catalytic surface at elevated temperatures. We identify metal atom diffusion as well as support atom mobility as important dynamical phenomena that enable the formation of new sites. We establish a protocol to identify transient sites by leveraging changes in nearest-neighbor coordination numbers in picosecond time scale simulations. Among the eight new sites that are distinct from prior experimental and DFT reports, two sites exhibit anionic, near-linear O–Pt–O configurations. Such configurations are neither intuitive nor easily located using static methods such as DFT. Therefore, DFT alone is not sufficient to obtain a complete, dynamic description of the catalytic surface. Based on the wide range of CO adsorbate affinities exhibited by the DFT- and AIMD-generated sites in this study, our aim going forward is to probe the dynamic surface response to adsorbate binding as well as site sensitivity of CO oxidation and water gas shift reaction kinetics.