Control and Manipulation of Gold Nanocatalysis: Effects of Metal Oxide Support Thickness and Composition

Control and tunability of the catalytic oxidn. of CO by gold clusters deposited on MgO surfaces grown on molybdenum, Mo(100), to various thicknesses are explored through temp.-programmed reaction measurements on mass-selected 20-atom gold clusters and via first-principles d. functional theory calcns. Au20 was chosen because in the gas phase it is characterized as an extraordinarily stable tetrahedral-pyramidal structure. Dependencies of the catalytic activities and microscopic reaction mechanisms on the thickness and stoichiometry of the MgO films and on the dimensionalities and structures of the adsorbed gold clusters are demonstrated and elucidated. Langmuir-Hinshelwood mechanisms and reaction barriers corresponding to obsd. low- and high-temp. CO oxidn. reactions are calcd. and analyzed. These reactions involve adsorbed O2 mols. that are activated to a superoxo- or peroxo-like state through partial occupation of the antibonding orbitals. In some cases, we find activated, dissociative adsorption of O2 mols., adsorbing at the cluster peripheral interface with the MgO surface. The reactant CO mols. either adsorb on the MgO surface in the cluster proximity or bind directly to the gold cluster. Along with the oxidn. reactions on stoichiometric ultrathin MgO films, we also study reactions catalyzed by Au20 nanoclusters adsorbed on relatively thick defect-poor MgO films supported on Mo and on defect-rich thick MgO surfaces contg. oxygen vacancy defects. [on SciFinder(R)]     «

Control and tunability of the catalytic oxidn. of CO by gold clusters deposited on MgO surfaces grown on molybdenum, Mo(100), to various thicknesses are explored through temp.-programmed reaction measurements on mass-selected 20-atom gold clusters and via first-principles d. functional theory calcns. Au20 was chosen because in the gas phase it is characterized as an extraordinarily stable tetrahedral-pyramidal structure. Dependencies of the catalytic activities and microscopic reaction mechanism...     »

CAN 150:127335 59-3 Air Pollution and Industrial Hygiene Lehrstuhl fur Physikalische Chemie, Technische Universitat Munchen, Garching, Germany. Journal 0002-7863 7439-98-7 (Molybdenum) Role: CAT (Catalyst use), USES (Uses) (MgO grown on support; control and manipulation of gold nanocatalysis: effects of metal oxide support thickness and compn.); 7440-57-5 (Gold) Role: CAT (Catalyst use), USES (Uses) (control and manipulation of gold nanocatalysis: effects of metal oxide support thickness and compn.); 124-38-9 (Carbon dioxide) Role: FMU (Formation, unclassified), FORM (Formation, nonpreparative) (control and manipulation of gold nanocatalysis: effects of metal oxide support thickness and compn.); 630-08-0 (Carbon monoxide) Role: POL (Pollutant), REM (Removal or disposal), OCCU (Occurrence), PROC (Process) (control and manipulation of gold nanocatalysis: effects of metal oxide support thickness and compn.); 1309-48-4 (MagnesiumOxide) Role: CAT (Catalyst use), FMU (Formation, unclassified), FORM (Formation, nonpreparative), USES (Uses) (films; control and manipulation of gold nanocatalysis: effects of metal oxide support thickness and compn.)     «

CAN 150:127335 59-3 Air Pollution and Industrial Hygiene Lehrstuhl fur Physikalische Chemie, Technische Universitat Munchen, Garching, Germany. Journal 0002-7863 7439-98-7 (Molybdenum) Role: CAT (Catalyst use), USES (Uses) (MgO grown on support; control and manipulation of gold nanocatalysis: effects of metal oxide support thickness and compn.); 7440-57-5 (Gold) Role: CAT (Catalyst use), USES (Uses) (control and manipulation of gold nanocatalysis: effects of metal oxide support thickness and c...     »