Synthesis of Reactive Co ₃ O ₄ /Nd ₂ Zr _{2– <i>x</i>} Ce _<i>x</i> O ₇ Catalysts via Tuning the Support Phase Structure and Oxygen Defect Abundance for Soot Combustion: The Dual-Optimization Strategy of Ce Bulk Doping and Co Surface Modification

Aiming to obtain efficient catalysts for soot particulate combustion, Nd 2 Zr 2– x Ce x O 7 ( x = 0, 0.4, 1, 1.6, 2) supports were designed and synthesized via the glycine combustion method and used to support Co 3 O 4 . With the increasing substitution amount of Ce for Zr, Nd 2 Zr 2– x Ce x O 7 gradually transforms from a disordered defect fluorite to a rare earth C-type phase, inducing a difference in lattice disorder degrees. For Nd 2 Zr 2– x Ce x O 7 supports, doping an appropriate amount of Ce at the Zr site enhances the soot combustion activity. Additionally, the supported Co 3 O 4 incorporates new oxygen vacancies, which promotes the formation of more redox sites beneficial for soot combustion. Among them, the defect-rich Co 3 O 4 /Nd 2 Zr 0.4 Ce 1.6 O 7 exhibits the best activity, attaining 50% soot conversion ( T 50 ) 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 Co 3 O 4 /Nd 2 Zr 0.4 Ce 1.6 O 7, further improving the catalytic activity, due to its superior NO oxidation capability and NO 2 utilization efficiency. In summary, the dual-optimization strategy of Ce bulk doping and Co surface modification can remarkably improve the catalytic performance of Nd 2 Zr 2 O 7, providing feasible guidance for the design of catalysts with practical application.