Comparison of surface chemistry of CeO₂ surfaces by single crystal and nanocrystal approaches

Chemistry at surfaces is frequently probed using oriented single crystal surfaces to explore the dependence of bonding and reactivity upon surface structure. Highly dispersed particles usually lack structural uniformity but can be probed by many more techniques and frequently with greater sensitivity due to their high surface area. Recent synthetic methods permit preparation of nanoparticles with high selectivity towards crystallite termination. We have undertaken an approach to study the chemistry of CeO₂ surface by direct comparison of certain probe molecules and test reactions on single crystal CeO₂(111) and (100) surface and upon nanoparticles that are grown with octahedral, cubic or rodlike morphologies that terminate with (111), (100) or mixed (100)+(110) terminations, respectively. We will report on studies of adsorption of O₂, methanol, formic acid and water on morphologically selected nanocrystals probed by Raman, FTIR and temperature programmed methods and will compare these with single crystal studies probed by sXPS, RAIRS and TPD.