Elucidating the Oxygen Activation Mechanism on Ceria-Supported Copper-Oxo Species Using Time-Resolved X-ray Absorption Spectroscopy

Rational design of better catalysts requires precise knowledge about the structure of active sites and their reactivity during catalytic cycle. However, for majority of catalytic systems and processes such information remains elusive due to large structural heterogeneity of catalytic material and various limitations of experimental and theoretical methods. Here, element specific operando spectroscopy helped us to gain such knowledge for copper-ceria system, which finds application in exhaust and sustainable energy catalysts. For this study, we have chosen the material with well-defined structure consisting of finely dispersed copper-oxo species (predominantly dimers) stabilized on ceria surface. Using times-resolved X-ray absorption spectroscopy we observed that oxidation states of copper and cerium atoms forming active sites change in concert allowing efficient catalytic oxidation of carbon monoxide below 100 ^oC. The developed methodology can be applied in future for more complex catalytic systems and processes to clarify complex structure-activity relationships.