Insight into the transient inactivation effect on Au/TiO 2 catalyst by in-situ DRIFT and UV-vis spectroscopy.

Au catalysts have drawn broad attention for catalytic CO oxidation. However, a molecular-level understanding of the reaction mechanism on a fast time-resolved scale is still lacking. Herein, we apply in situ DRIFTS and UV-Vis spectroscopy to monitor the rapid dynamic changes during CO oxidation over Au/TiO 2 . A pronounced transient inactivation effect likely due to a structural change of Au/TiO 2 induced by the reactants (CO and O 2 ) is observed at the beginning of the reaction. The transient inactivation effect is affected by the ratio of CO and O 2 concentrations. More importantly, during the unstable state, the electronic properties of the Au particles change, as indicated by the shift of the CO stretching vibration. UV-Vis spectroscopy corroborates the structure change of Au/TiO 2 surface induced by the reactants, which leads to a weakening of the Au catalyst's ability to be oxidized (less O 2 adsorption), resulting in the transient inactivation effect.