(710b) Single Atom Catalyst for Oxidation - Understanding the Fundamentals of Synthesis and Reactivity

Understanding the synthesis of single atom catalysts and the underlying metal-support interaction is crucial in improving the anti-sintering capability during chemical reactions. Strong electrostatic adsorption (SEA), which relies on an electrostatic driving force for the deposition of appropriately charged metal precursors on an oppositely charged metal oxide surface, demonstrates considerably higher weight loading threshold than for incipient wetness. Our study combines density functional theory (DFT) calculations and solution phase isothermal titration calorimetry (ITC) adsorption experiments to examine charged and solvated precursor adsorption onto ceria nano-cubes. DFT calculations bridge from an isolated gas phase metal atom and a single crystal plane of oxide surface to a ligated metal atom and bulk oxide surface (with a mixture of different crystal planes) in solution phase. We demonstrate agreement between DFT and ITC adsorption energy trends, towards developing a predictive framework for the stability of precious group metal (PGM) precursors under solid-liquid synthesis conditions. Our SEA adsorption model considers mainly electrostatics, with charge separated over the ligated complexes and the support surface. We use DFT to model the adsorption including partial deligation of the precursor, examining how the ligand chemical potential can alter adsorption thermodynamics.

We also examined CO oxidation kinetics over the single atom catalysts on ceria. DFT calculations in conjugation with experiments examine the catalytic performance and identify the synergy between individual metal atoms and the support towards CO oxidation. The emphasis is laid on specific metal-support interaction via structural relaxation or electronic structure induced by the presence of the adatom.