Interaction-Induced Self-Assembly of Au@La₂O₃ Core–Shell Nanoparticles on La₂O₂CO₃ Nanorods with Enhanced Catalytic Activity and Stability for Soot Oxidation

The sintering resistance of supported Au nanoparticle (NP) catalysts is crucial to their practical application in heterogeneous catalysis reactions. Herein, a series of Au@La₂O₃ core–shell nanoparticle catalysts supported on the surfaces of La₂O₂CO₃ nanorods (Au_n@La₂O₃/LOC-R) were successfully synthesized via the method of interaction-induced self-assembly. Supported Au NPs with uniform size are deposited on the surfaces of La₂O₂CO₃ nanorods by the gas bubbling-assisted membrane reduction (GBMR) method. La₂O₃ shell layers spontaneously formed and then partially coated the surface of Au NPs for interaction-induced self-assembly of Au@La₂O₃ core–shell NPs during the process of calcination at 600 °C. The strong interaction between Au NPs and La₂O₃ oxides increases the density of active sites (oxygen vacancies) for enhancing the adsorption–activation properties of O₂. Au_n@La₂O₃/LOC-R catalysts show high catalytic activity and stability for soot oxidation under the conditions of loose contact between soot and catalyst. The catalytic activities (T₅₀, TOF) of Au₄@La₂O₃/LOC-R catalyst for soot oxidation are 375 °C and 1.15 × 10^–3 s^–1, respectively. On the basis of the results of various physicochemical characterizations, the strong metal (Au)–oxide (La₂O₃) interactions and the increase in active oxygen species of Au_n@La₂O₃/LOC-R catalysts are responsible for enhancing the catalytic activity of soot oxidation. The Au@La₂O₃ core–shell nanostructure can improve catalytic stability and suppress sintering of supported Au NPs during catalytic soot oxidation. The catalytic mechanism of soot oxidation is proposed and discussed, in which the catalytic oxidation of NO to NO₂ over Au@La₂O₃ core–shell NPs is the key step for catalytic soot oxidation; the active sites at the interface of the Au core and La₂O₃ shell can promote catalytic NO oxidation. Au_n@La₂O₃/LOC-R catalysts show promise in practical applications for diesel soot oxidation.