Atomically dispersed Zr neighboring Pd sites in ceria for stabilization and enhanced performance in passive NOx adsorbers

The design of Passive NO x Adsorbers (PNA) is essential for controlling cold-start emissions, yet Pd-ceria systems often encounter limitations in storage capacity and hydrothermal durability. In this work, we stabilize Pd by incorporating atomically dispersed Zr as neighboring atoms in ceria, establishing a framework for efficient and stable NO x capture. Zr doping in CeO 2 modifies the electronic environment by intensifying Pd-O hybridization and broadening electronic states near the Fermi level. These modifications, alongside emergent Pd-O-Zr interfacial sites, facilitate the dynamic reconfiguration of oxygen vacancies. This process promotes the oxidation of NO to NO 2 , enabling the optimized catalyst to yield a NO x storage capacity of 166.6 µmol/g cat —a value that surpasses the theoretical limit derived from Pd content. Structural stabilization further underpins these performance gains. Zr doping reinforces the CeO 2 lattice, enhancing the thermal resilience of the support. Simultaneously, the atomically dispersed Zr adjacent to Pd sites modulates metal-support interactions to an optimal state, effectively inhibiting Ostwald ripening, particle migration, and coalescence. These combined effects significantly improve hydrothermal stability under rigorous conditions. Our findings provide a mechanistic basis for the rational design of high-performance PNA and offer a viable pathway to mitigate cold-start NO x emissions in advanced after treatment systems.