Site-Sensitivity of CO Oxidation Kinetics Catalyzed by Atomically Dispersed Pt1/TiO2

The local coordination environment of the single atom in an atomically dispersed catalyst (ADC) plays a crucial role in determining its catalytic activity and stability. This study combines density functional theory, ab initio molecular dynamics, and kinetic modeling to investigate the effect of local coordination on CO oxidation kinetics. We explore the kinetics across six representative Pt binding sites on the rutile-TiO2 (110) surface, spanning adatoms placed at basal and bridging sites of TiO2, anionic and cationic vacancies, and two oxidized surfaces. The Tivac site, in which Pt is bound to a cationic vacancy, yields the highest turnover frequency (TOF) via the Mars-van Krevelen-type mechanism. Another binding site featuring a square planar PtO4 complex exhibits the lowest apparent activation energy at room temperature. We also observe variations in rate orders and rate-determining steps across different binding sites and reaction temperatures. We uncover a volcano relationship between CO and O2 adsorption energies and TOFs, indicating the profound role of the local coordination environment in atomically dispersed catalysis. Our findings shed light on the importance of understanding and controlling the distribution of binding sites in ADCs to maximize their potential in catalysis applications.