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-Optim

Aiming to obtain efficient catalysts for soot particulate combustion, Nd₂Zr_2-<i>x</i>Ce_<i>x</i>O₇ (<i>x</i> = 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-<i>x</i>Ce_<i>x</i>O₇ gradually transforms from a disordered defect fluorite to a rare earth C-type phase, inducing a difference in lattice disorder degrees. For Nd₂Zr_2-<i>x</i>Ce_<i>x</i>O₇ 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 (<i>T</i>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 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.