Tracking the formation, fate and consequence for catalytic activity of Pt single sites on CeO2

Platinum single sites are highly attractive due to their high atom economy and can be generated on CeO(2)by an oxidative high-temperature treatment. However, their location and activity are strongly debated. Furthermore, reaction-driven structural dynamics have not been addressed so far. In this study, we were able to evidence platinum-induced CeO(2)surface restructuring, locate platinum single sites on CeO(2)and track the variation of the active state under reaction conditions using a complementary approach of density functional theory calculations, in situ infrared spectroscopy, operando high-energy-resolution fluorescence detected X-ray absorption spectroscopy and catalytic CO (as well as C(3)H(6)and CH4) oxidation. We found that the onset of CO oxidation is linked to the migration of platinum single sites from four-fold hollow sites to form small clusters containing a few platinum atoms. This demonstrates that operando studies on single sites are essential to assess their fate and the resulting catalytic properties.