Ag-incorporated macroporous CeO2 catalysts for soot oxidation: Effects of Ag amount on the generation of active oxygen species

•Ag-incorporated macroporous CeO2 catalysts were synthesized with various Ag amounts.•The amount of Ag affects the surface oxygen vacancies of CeO2.•The diverse surface oxygen vacancies of catalysts induced the different ability to generate active oxygen species.•The appropriate amount of Ag on CeO2 resulted in improved O2− generation.•Superior soot oxidation activity was achieved with optimum Ag amount.