andAu-CeO2-δduringCOOxidation.PDF

Supporting Information Available: Raman Analysis of Mode Softening in Nanoparticle CeO2-δ and Au-CeO2-δ during CO Oxidation Youjin Lee,1 Guanghui He,1 Austin J. Akey,1 Rui Si,2 Maria Flytzani-Stephanopoulos,2 and Irving P. Herman*1 1 Department of Applied Physics and Applied Mathematics Columbia University, New York, NY 10027 2 Department of Chemical and Biological Engineering Tufts University, Medford, MA 02155 * Corresponding author iph1@columbia.edu 1. Residual gas analysis of flow after passing over ceria nanoparticles Figure S1 shows the mass 44 signal of CO2 measured in the residual gas analyzer (RGA) after CO flow over ceria nanoparticles during heating and cooling cycles for a variety of conditions. The temperature was increased to 25 °C intervals from 0 to 100 °C and to 100 °C intervals afterwards. Between intervals the heating/cooling rate was 50 °C/min. The temperature was kept constant at the intervals for 10 min. Figure S1a shows the relative CO reactivities for different shapes of particles. Figure S1b shows the change in reactivity for different flow mixtures. The production of CO2 increases when O2 gas is incorporated into the gas flow. S １ Figure S1. RGA results showing CO2 (mass 44) product at various temperatures. (a) CeO2 nanorods (blue), Au-CeO2 nanorods (black), Au-CeO2 polyhedra (green), and Au-CeO2 cubes (red) with the same flow condition (20 sccm, 5% CO/He) and (b) CeO2 and Au-CeO2 nanorods with 1% CO/0.5% O /He flow and Au-CeO nanorods with 1% CO/He flow. The 2 2 arbitrary units are the same in both parts. 2. Reaction pathways of CO oxidation