| Abstract
| - NO2 adsorption at a BaO(100) surface is investigated by means of spin polarized GGA density functionaltheory. A periodic supercell procedure is employed, and two redox reaction channels are mapped out, involvingtwo chemisorbed NO2 molecules per supercell. The chemisorption is studied in two subsequent steps. Thereaction paths are initiated by NO2 adsorption in the form of a nitrite over a Ba2+ site. This generates anelectron hole among the surrounding surface oxygen atoms. A reaction path branching occurs as the secondNO2 either (a) acts as surface oxidant, forming a surface nitrite−peroxide pair by releasing NO(g), or (b)binds to an O-surf site to form a formal surface nitrate. A redox reaction involving surface nitrite−nitrateinterconversion is also addressed. The computed results are employed to interpret experimental observationsof surface nitrites, peroxides, NO(g) desorption, and surface Ba(NO3)2 formation. The understandings arediscussed in the context of the NOx storage concept of lean-burn catalysis.
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