Surface and reduction energetics of the CeO2-ZrO2 catalysts

The (110), (111), and (310) surfaces of cubic CeO2-ZrO2 solid solutions have been studied by computer simulation techniques using atomistic models. Surface energies, Ce4+/Ce3+ reduction energies, and penetration profiles of oxygen vacancy formation have been calculated. The results of the calculations suggest some possible factors that could explain the increase in the oxygen storage capacity experimentally observed in these systems relative to pure ceria: surface Ce4+/Ce3+ reduction energies are comparable with previously found bulk values; introduction of zirconia into the ceria lattice decreases the Ce4+/Ce3+ reduction energy on the stable (110) and (111) surfaces; oxygen vacancies tend to segregate to these surfaces.