Influence of an external electric field on the catalytic CO oxidation of nanoscaled CeO2 and its La3+ and Gd3+ congeners.

Herein, we investigate how aliovalent doping and application of an external electrical field modulates the catalytic activity of nanoscale ceria (nCeO2) towards CO oxidation. Gd3+ and La3+ were doped into the nCeO2 lattice. Such doping influences the concentration and mobility of oxygen vacancies, which are promoting CO oxidation to CO2. When applying an electric potential, charge transport within nCeO2 is modulated. Our results show that both dopants Gd3+ and La3+ lead to an increasing VO concentration, whereas the impact of the applied potential on the oxidation behaviour varies with catalyst composition. The applied electric potential markedly improves the activity of undoped nCeO2 and 5% Gd3+-doped nCeO2; however, it causes no significant change in CO oxidation capability in 2.5% Gd3+-doped and La3+-doped samples. These findings can be understood considering the applied potential and its influence on the polaron mobility and VO arrangement, which are controlled by the underlying oxidic defect structure.