The synthesis and characterization of Ir and Pt single atoms supported on MgAl2O4 by multiple in situ/operando techniques will be presented. We show that single atoms are stabilized by strong covalent bonds with specific sites on the support as evidenced by x-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations. Infrared spectroscopy and XAS show that Ir and Pt single-atoms have unique structural and electronic properties which is reflected in the dramatically different CO adsorption strength and geometry compared with CO adsorption on nanoparticles. We show that oxygen activation on CO saturated single atoms is a kinetically facile step. Additionally, under reaction conditions, we show that CO and O are co-adsorbed on single atoms and the CO acts as a spectator during the catalytic cycle. The mechanistic consequences of the spectator CO, facile O2 activation and co-adsorption of CO and O on CO oxidation kinetics on single atoms will be presented and the reaction mechanism will be elucidated using detailed kinetics measurements, in operando XAS and DFT calculations.

CO oxidation on supported Ir and Pt single atoms: Structural and kinetic study

255th National Meeting (2018)

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