Synthesis of Reactive Co₃O₄/Nd₂Zr_2-xCe_xO₇ Catalysts via Tuning the Support Phase Structure and Oxygen Defect...

Aiming to obtain efficient catalysts for soot particulate combustion, Nd₂Zr_2-xCe_xO₇ (x = 0, 0.4, 1, 1.6, 2) supports were designed and synthesized via the glycine combustion method and used to support Co₃O₄. With the increasing substitution amount of Ce for Zr, Nd₂Zr_2-xCe_xO₇ gradually transforms from a disordered defect fluorite to a rare earth C-type phase, inducing a difference in lattice disorder degrees. For Nd₂Zr_2-xCe_xO₇ supports, doping an appropriate amount of Ce at the Zr site enhances the soot combustion activity. Additionally, the supported Co₃O₄ incorporates new oxygen vacancies, which promotes the formation of more redox sites beneficial for soot combustion. Among them, the defect-rich Co₃O₄/Nd₂Zr_0.4Ce_1.6O₇ exhibits the best activity, attaining 50% soot conversion (T₅₀) at 346 °C with the assistance of NO. The introduction of NO into the reaction feed leads to the formation of various reactive nitrite/nitrate intermediates on Co₃O₄/Nd₂Zr_0.4Ce_1.6O₇, further improving the catalytic activity, due to its superior NO oxidation capability and NO₂ utilization efficiency. In summary, the dual-optimization strategy of Ce bulk doping and Co surface modification can remarkably improve the catalytic performance of Nd₂Zr₂O₇, providing feasible guidance for the design of catalysts with practical application.