Effects of Light on Catalytic Activities and Lifetime of Plasmonic Au Catalysts in the CO Oxidation Reaction

The catalytic oxidation of CO to CO, allows for the removal of poisonous CO to improve indoor and outdoor air quality. Currently, industrial CO oxidation catalysts are not effective at low temperatures. A group of the most promising choices, Au catalysts supported on Mg(OH)(2) and MgO, are highly active even at -70 degrees C, but show decreased activity between 20 and 100 degrees C. These catalysts also have short lifetimes. Here, we utilize knowledge of plasmonic catalysis in the study of the CO oxidation reaction over plasmonic Au catalysts. We hypothesized that light interacting with catalysts via surface plasmon resonances has the potential to dramatically improve such catalytic reactions. Initial experiments demonstrated a significant improvement of the catalytic activity and lifetime under light. Using the particular features in the temperature dependent conversion curve of this catalyst, we developed a method to separately examine the thermal and nonthermal contributions of light. Detailed studies on the relationship between light induced desorption of CO2 and the regeneration of catalytic activity provided evidence for a mechanism: the main effect of light, in addition to light induced heating, is the removal of surface carbonates which otherwise poison the catalyst. This approach allows for dramatically increased catalytic activity and lifetime, demonstrating a path for highly active CO oxidation over a wide range of temperatures. Such a light enhanced catalytic reaction might find wide applications to replace current CO oxidation systems.