A DFT study of pseudomorphic monolayer Pt and Pd catalysts for NOx storage reduction applications

Pseudomorphic monolayer catalysts involving Pd and Pt monolayers above late transition metal (TM) hosts (Cu, Ru, Rh, Ag, Ir and Au) were examined for the oxidation of NO with atomic oxygen. It is found that for systems in which the lattice constant of Pt (or Pd) is expanded, the reaction enthalpy is more endothermic and the reaction barrier is higher. Conversely, for systems under compression, NO2 formation is more exothermic and has a lower barrier. These systems were also examined for their thermodynamic stability upon adsorption of NO and oxygen. Although, segregated systems with a pseudomorphic monolayer of Pt and Pd above a transition metal were found to be stable for systems involving Ru, Ir, Rh and Au even in the presence of adsorbates, oxygen was found to be capable of reversing the position of the supported monolayer and the host metal for systems involving Ag or Cu.