(720d) CO Oxidation Kinetics on Supported Ir Single Atoms

MgAl₂O₄ supported Ir single atoms were synthesized and characterized by multiple in situ/operando techniques. We show that Ir single atoms are stabilized by strong covalent bonds with the support as evidenced by x-ray absorption spectroscopy (XAS). The O and Al and the hydroxyl groups from the support act as ligands affecting the Ir electronic properties as shown by XAS and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of adsorbed CO. DRIFTS of adsorbed CO shows the formation of a remarkably stable Ir(CO)₃. The Ir(CO)₃ structure is supported by chemisorption measurements and DFT calculations. The mechanistic consequences of the Ir(CO)₃ on CO oxidation kinetics will be presented and the reaction mechanism will be compared with that on Ir nanoparticles.