A robust core-shell silver soot oxidation catalyst driven by Co3O4: Effect of tandem oxygen delivery and Co3O4-CeO2 synergy

In this work, tandem oxygen delivery systems were built by coating cube-like Co3O4 with Ag/CeO2, which exhibited high soot oxidation activity that overwhelmed the Fe2O3-based catalysts. The results of TPR and activity tests indicated that a large amount of Co3O4 lattice oxygen could be transferred into O-x(-) with the assistance of Ag/CeO2. These active oxygen species accelerated the oxidation of soot and NO at low temperature. Furthermore, the Co3O4-CeO2 synergy facilitated Co3+ -> Co2+ transformation during reactions, resulting in boosted NO conversion and thereby NO2-assisted soot combustion at mild and high temperatures. Given the Ag/Co3O4@CeO2-type catalysts were low-cost, hydrothermally stable and could be fabricated via co-precipitation methods easily, they were highly promising for application in both gasoline and diesel particulate filters.