Partially reduced PdOx nanoparticles strongly interacting with defect-rich ceria via dynamic redox pulse for complete methane oxidation

Tuning the surface structures of active metal species to desired states is a rational approach to achieve high performance in heterogeneous catalysis. However, modulating the coordination environments and electronic states while maintaining a consistent nanoparticle size remains challenging. This difficulty has led to controversial findings regarding the optimal surface structures of supported palladium nanoparticles for complete methane (CH4) oxidation. In addition, palladium catalysts are vulnerable to deactivation during reactions due to inadequate anchoring effects on support materials. Herein, we engineer the PdOx nanoparticles with low oxygen coordination and a partially reduced Pdδ+ (0 < δ < 2) state via a dynamic redox pulse method. During this process, oxygen vacancy defects on ceria are simultaneously enriched, thereby establishing strong interaction that immobilizes the PdOx nanoparticles. The PdOx catalyst exhibits superior activity for CH4 oxidation under wet conditions, outperforming other ceria-supported palladium nanoparticles. Furthermore, the reinforced interaction endows remarkable structural robustness, preventing deactivation under harsh reaction conditions. Theoretical simulations elucidate the redox-driven transformation and stabilization of palladium species, establishing a direct structure-activity relationship among distinct palladium motifs for CH4 activation. The PdOx catalyst demonstrates consistent performance in bench-scale reactions, offering valuable design strategies for optimally nanostructured palladium catalysts for complete CH4 oxidation.