An exploration of soot oxidation over CeO2-ZrO2 nanocubes: Do more surface oxygen vacancies benefit the reaction?

CeO2, Ce20Zr1 and Ce10Zr1 mixed oxides with uniform nanocubic morphology and varied amounts of surface oxygen vacancies were synthesized to study the influence of surface oxygen vacancies on soot catalytic oxidation in a low concentration of gaseous O2. It is presented that excessive surface oxygen vacancies may lead to low soot oxidation activity and catalyst deactivation during the reaction. H2-TPR results indicate that the doping of Zr does not decrease the amount of surface redox sites. Instead, it induces the formation of surface capping oxygen (O2−) rather than the highly active Ox− species, which hereby affects the catalyst behavior significantly. These point out that a ceria-based catalyst should not contain too many surface oxygen vacancies when designing for the application in gasoline particulate filters.