Structure and electronic properties of Ca-doped CeO2 and implications on catalytic activity: An experimental and theoretical study

Doping CeO2 with for example, Ca gives an enhanced reactivity toward reduct ion of SO2 by CO, and total combustion of methane. Theoretical modeling usi ng static minimizations and molecular dynamics (MD) simulations of the dope d (110) face in combination with ab initio quantum chemical cluster models shows large effects on the Ce(IV)/Ce(III) balance due to the doping. Comput ed oxygen-to-cerium charge-transfer energies are strongly reduced as a resu lt of the introduction of defects and oxygen vacancies, but not sufficientl y to explain the observed reactivities. The structures resulting from the M D simulations for both the doped and undoped material are in good agreement with recent experimental pulsed neutron scattering results.