(570al) Theoretical Investigation of the Three-Phase Boundary of Ceria Supported Noble Metal Clusters

Precious metal nanoparticles supported on reducible oxides are known to exhibit excellent activity and selectivity for the water-gas shift reaction (WGS) which is a key step in fuel processing to maximize hydrogen yield and for providing clean hydrogen. It has been proposed that the three-phase boundary (TPB) of a gas-phase, the reducible oxide surface, and the metal cluster constitutes in these materials the active site for catalysis and that possibly each active phase can be adjusted to activate different key reaction steps in the WGS. In this work, we studied the interaction of small Pt and Au clusters on the CeO2(111) surface and their effect on the reducibility of the oxide support using first-principles electronic structure calculations based on the DFT+U method. Furthermore, we calculated reaction intermediates and transition states for selected reaction pathways of the WGS reaction. All transition states were identified by combining the nudged elastic band method with the dimer method. Overall, it seems that the TPB constitutes a unique reaction environment for catalysis with each phase affecting the properties of the other active phase.