Mechanistic Insights\ninto Potassium-Assistant Thermal-Catalytic\nOxidation of Soot over Single-Crystalline SrTiO<sub>3</sub> Nanotubes\nwith Ordered Mesopores

Soot\ncatalytic combustion using single-crystalline perovskite-type\nmaterials holds great promise as an efficient non-noble metal catalyst,\nwith K<sup>+</sup>-modified SrTiO<sub>3</sub> emerging as one of the\nmost desirable candidates. However, balancing the crystallinity and\nan optimized pore structure and revealing the mechanism underlying\nthe K<sup>+</sup> action remain challenges. Herein, by the electrospinning\ntechnique, we successfully self-assembled the K-doped single-crystalline\nSrTi<sub>0.95</sub>Al<sub>0.05</sub>O<sub>3</sub> nanotubular webs\nwith ordered mesopores. The good crystallinity and mesoporous structures\ncontribute to the enhanced catalytic performance with desirable stability.\nBased on comprehensive characterizations and density functional theory\n(DFT) calculations, K<sup>+</sup> ions effectively accumulate defect\ncharges, facilitating the generation of additional oxygen vacancies\nand expediting oxygen activation during the reaction. Additionally,\nthe presence of K<sup>+</sup> ions prefers to preserve O<sub>2</sub> bond integrity during activation, significantly increasing NO adsorption\ncapacity. Utilizing KNO<sub>3</sub> as the medium, K<sup>+</sup> effectively\nfacilitates the storage and subsequent release of active oxygen species,\nleading to the promised catalytic performance (<i>T</i><sub>50</sub> = 368 °C, <i>E</i><sub>a</sub> = 64.97 kJ\nmol<sup>–1</sup>, TOF<sub>K</sub> = 0.017 h<sup>–1</sup>). This study provides mechanistic insights into developing advanced\nmaterials for thermal catalytic heterogeneous reactions.