Catalytic Decomposition of Ba(NO3)2 on Pt(111)

The decomposition of Ba(NO3)(2) formed on BaO/Pt(111) (Pt(111) surface is partially covered by BaO) in the presence of CO was studied using temperature-programmed desorption, infrared reflection absorption, and X-ray photoelectron spectroscopies. The exposure of BaO/Pt(111) to elevated NO2 pressure (1.0 X 10(-4) torr) at 450 K leads to the formation of Ba(NO3)(2), chemisorbed 0 (O-Pt), and Pt-oxide-like domains. During TPD, the Ba(NO3)(2) begins to thermally decompose near 490 K, releasing NO and NO2 with the maximum NOx desorption rate seen at 605 K. The O-Pt species formed following the exposure of BaO/Pt(111) to NO2 react with CO to release CO2 at 450 K. The consumption of O-Pt during CO oxidation initiates the migration of 0 from the Pt-oxide-like domains to the chemisorbed phase, where the CO oxidation reaction occurs. Therefore, the removal of O-Pt by CO leads to the reduction of oxidized Pt and to the formation of metallic Pt(111) domains, where, subsequently, catalytic decomposition of Ba(NO3)(2) can take place. The Pt-catalyzed decomposition of Ba(NO3)(2) occurs readily at 450 K, a temperature much lower than the onset of the decomposition temperature of Ba(NO3)(2) in the presence of oxidized Pt.