A characterization study of platinum-tin oxide films supported on Al 2O 3

Abstract

Films which are about 20 Å thick containing platinum and tin oxide were produced by impregnating γ-Al 2O 3 in an acetone solution containing stannic chloride and chloroplatinic acid. Electron spectroscopy for chemical analysis, Auger electron spectroscopy, temperature-programmed decomposition and depth profiling were used to characterize these films after oxidation in air at 725 K and after reduction in hydrogen at 1 atm and 775 K. Both CO and H 2O are incorporated in these films but in different relative amounts in the oxidized and reduced samples. The desorption characteristics also differ between the oxidized and reduced samples, but H 2O and CO desorb simultaneously from each type of sample. Electron spectroscopy for chemical analysis shows that the interaction between the platinum and tin is through a Pt-O-Sn bond which is present in both oxidized and reduced samples. Reduction converts PtO and PtO 2 to metallic platinum and causes sintering of platinum crystallites to bulk-like platinum.