(689c) Active Site Dynamics in Atomically Dispersed Catalysts

Recent developments in catalysis focus on enhancing catalytic efficiency by atomically dispersing Pt-group and noble metals on support surfaces, predominantly for oxidation chemistry. While microscopy and spectroscopy combined with computational studies yield critical insights into the location and coordination of these metal centers, the study of operando characteristics can be challenging. Our goal is to employ a multiscale approach combining quantum chemistry with ab initio molecular dynamics (AIMD) to determine the distribution of active sites obtained under reaction conditions for Pt-group metals on oxide supports. Using the DFT-optimized binding sites as starting candidates, we carry out 5ps NVE simulations of the active site on both pristine and defective (110) surfaces of rutile TiO₂ to probe the range of stable and metastable configurations adopted by the metal center at 500K. While our work is preliminary, a distribution of active sites – resulting from thermally induced migration, subsurface migration (which is challenging to detect with microscopy), or support atom migration – is expected to emerge. This analysis lays the foundation for further surface chemistry and site-averaged kinetics studies. Going forward, the outcomes of this study will also enable us to examine the little-understood impact of these picosecond fluctuations on steady state kinetics.