Active role of the support in NOx storage and reductioncatalytic systems

We present first-principles density functional theory calculations of the adsorption properties of NO2 and SO2 on isolated (BaO)(n) (n = 1, 2, 4, 6, 8, 9) clusters as well as on small BaO clusters ((BaO)(n) with n = 1, 2, 4) supported on the anatase TiO2(001) surface. The TiO2 support influences binding indirectly by enhancing the electron donation from the BaO clusters to both chemisorbed NO2 and the support. This support-mediated increase in stability is not observed for SO2. We describe in detail and highlight the role played by TiO2 on the charge transfer mechanism, which can be used to control the catalytic properties of the active components of nitrogen storage and reduction catalytic systems. The relatively larger activity of the supported BaO clusters towards NO2 adsorption in comparison to SO2 could in principle offer protection against sulfur poisoning.