(765d) Structural and Kinetic Study of CO Oxidation on Single Atom Pt/CeO2
We report CO oxidation kinetics, density functional theory (DFT) calculations and in-situ/operando characterization of CeO2 supported Pt single atoms to identify the Pt active complex and reaction mechanism. The Pt single atoms supported on CeO2 were synthesized by atom trapping and characterized by microcalorimetry of CO and O2 adsorption, aberration corrected scanning transmission electron microscopy, in-situ aberration corrected high resolution transmission electron microscopy, in-situ infrared spectroscopy and operando x-ray absorption spectroscopy. We identified the Pt anchoring site on CeO2 step sites using in-situ/operando EXAFS and the results show that the active Pt complex is generated under CO oxidation reaction conditions. A proposed CO oxidation reaction mechanism will be presented based on the measured kinetics, DFT calculations and in-situ/operando DRIFTS and EXAFS. Additionally, the effect of CO and O2 pulses at different temperatures on the Pt stability, local coordination and activity for CO oxidation will be presented.