Mechanistic Insights into Potassium-Assistant Thermal-Catalytic Oxidation of Soot over Single-Crystalline SrTiO3 Nanotubes with Ordered Mesopores

Soot catalytic combustion using single-crystalline perovskite-type materials holds great promise as an efficient non-noble metal catalyst, with K+-modified SrTiO3 emerging as one of the most desirable candidates. However, balancing the crystallinity and an optimized pore structure and revealing the mechanism underlying the K+ action remain challenges. Herein, by the electrospinning technique, we successfully self-assembled the K-doped single-crystalline SrTi0.95Al0.05O3 nanotubular webs with ordered mesopores. The good crystallinity and mesoporous structures contribute to the enhanced catalytic performance with desirable stability. Based on comprehensive characterizations and density functional theory (DFT) calculations, K+ ions effectively accumulate defect charges, facilitating the generation of additional oxygen vacancies and expediting oxygen activation during the reaction. Additionally, the presence of K+ ions prefers to preserve O2 bond integrity during activation, significantly increasing NO adsorption capacity. Utilizing KNO3 as the medium, K+ effectively facilitates the storage and subsequent release of active oxygen species, leading to the promised catalytic performance (T50 = 368 °C, Ea = 64.97 kJ mol–1, TOFK = 0.017 h–1). This study provides mechanistic insights into developing advanced materials for thermal catalytic heterogeneous reactions.