Chemisorption and reactivity of nitric oxide on Na-dosed platinum{111}

Abstract

The adsorption of NO on a sodium-precovered Pt{111} single crystal has been studied by temperature-programmed desorption (TPD) and the resulting sodium species characterised by Na KL _2,3 L _2,3 ¹ D X-ray excited Auger electron spectroscopy (XAES). Sodium strengthens the adsorption of NO and promotes its dissociation. At sufficiently high sodium coverages, all the adsorbed NO is dissociated and N ₂ is the only nitrogen-containing desorption product: no N ₂ O is observed. Na-promoted NO does not react with O _a to form a surface nitrite. Differences between these results and previous work on K/Pt{111} prompted investigation of the effect of NO ₂ impurity in the dosing gas. It was found that this could account for the observed differences. The surface sodium nitrite formed by NO ₂ dosing was shown by XAES to be agglomerated and gave rise to a signal at 990.0 eV compared to 994.8 eV for clean sodium and 993.0 eV for sodium in the presence of NO.