15 - Direct photocatalysts on optically excited plasmonic metal nanostructures of coinage metals
Andiappan Marimuthu1, Hongliang Xin1, Phillip Christopher2, Suljo Linic1, email@example.com. (1) Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, United States, (2) Department of Chemical and Environmental Engineering, UC Riverside, Riverside, CA 92521, United States
Ever since the reports by Fujishima and Honda that TiO2 illuminated with low intensity UV radiation could split water, the field of heterogeneous photo-catalysis has almost exclusively focused on semiconductor photo-catalysts. Herein, we report on a new family of photo-catalysts that can efficiently couple thermal energy and photonic stimuli to drive photo-chemical transformations with unprecedentedly high efficiencies. These materials are plasmonic nanostructures of coinage metals.
We show that the underlying mechanisms governing photo-chemical bond making (breaking) on plasmonic metals are fundamentally different than on semiconductors. Consequently, plasmonic metals exhibit profoundly different behavior compared to semiconductor photo-catalysts. For example, unlike semiconductors, these materials exhibit a positive relationship between reaction rates (and quantum efficiencies) and light intensity. Also, plasmonic nanostructures exhibit an exponential increase of photo-catalytic rate (and quantum efficiency) on operating temperature. Typical semiconductors show lower photo-catalytic rates at higher temperatures. As a result, at elevated temperatures and source intensities, plasmonic nanostructures operate with very high quantum efficiencies (near unity).
We have developed a molecular model based on first-principles calculations that describes photo-chemical transformations on plasmonic metals. We show that the model captures the unique, experimentally observed features of the photo-catalytic processes on plasmonic metals.
[ol][li]Suljo Linic, Phillip Christopher and David B. Plasmonic-metal nanostructures for efficient conversion of solar to chemical energy, Nature Materials, 10 , 911, 2011.[/li][li]P. Christopher, H. Xin, S. Linic, Visible light enhanced catalytic oxidation reactions on plasmonic silver nanostructures, Nature Chemistry, 3, 467, 2011.[/li][/ol]
Sunday, August 19, 2012 03:50 PM
Surface Science of Catalysis (01:15 PM - 04:30 PM)
Location: Doubletree by Hilton Philadelphia Center City
Room: Aria A/B