Oxygen adsorption and dissociation on yttria stabilized zirconia surfaces

We have modelled the nature of oxygen species on the surfaces of yttrium stabilized zirconia (YSZ) in relation to its application as a catalyst for partial oxidation of methane. Quantum mechanical DFT-GGA calculations have been carried out to characterize the interaction between oxygen molecules and the perfect ZrO2 and defective YSZ (111) planar and stepped surfaces. In general, the results suggest that the creation of oxygen vacancies by yttrium doping provides an active site for oxygen adsorption. Depending on the topography and defect dispersion, various oxygen intermediates have been identified and analyzed by their density of states. The low-coordinated Zr cations on the YSZ surfaces can attract strongly reduced oxygen species and the most stable adsorption state of oxygen achieves a higher bond saturation of the neighbouring Zr site. In addition, the probable reaction pathways have been predicted for oxygen dissociation on the plane and stepped (111) surfaces of YSZ.