Zhang Lei, Niu Yiming, Pu Yinghui, Wang Yongzhao, Dong Shaoming, Liu Yuefeng, Zhang Bingsen, Liu Zhong-Wen
Key Laboratory of Syngas Conversion of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710119, China.
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.
Nano Lett. 2023 Dec 27;23(24):11999-12005. doi: 10.1021/acs.nanolett.3c04008. Epub 2023 Dec 15.
Redispersion is an effective method for regeneration of sintered metal-supported catalysts. However, the ambiguous mechanistic understanding hinders the delicate controlling of active metals at the atomic level. Herein, the redispersion mechanism of atomically dispersed Pt on CeO is revealed and manipulated by techniques combining well-designed model catalysts. Pt nanoparticles (NPs) sintered on CeO nano-octahedra under reduction and oxidation conditions, while redispersed on CeO nanocubes above ∼500 °C in an oxidizing atmosphere. The dynamic shrinkage and disappearance of Pt NPs on CeO (100) facets was directly visualized by TEM. The generated atomically dispersed Pt with the square-planar [PtO] structure on CeO (100) facets was also confirmed by combining Cs-corrected STEM and spectroscopy techniques. The redispersion and atomic control were ascribed to the high mobility of PtO at high temperatures and its strong binding with square-planar O sites over CeO (100). These understandings are important for the regulation of atomically dispersed platinum catalysts.
再分散是烧结金属负载型催化剂再生的一种有效方法。然而，对其机理的模糊认识阻碍了在原子水平上对活性金属的精确控制。在此，通过结合精心设计的模型催化剂的技术，揭示并操控了原子分散在CeO上的Pt的再分散机理。在还原和氧化条件下，Pt纳米颗粒（NPs）烧结在CeO纳米八面体上，而在氧化气氛中，温度高于约500°C时，Pt纳米颗粒会再分散在CeO纳米立方体上。通过透射电子显微镜（TEM）直接观察到了CeO（100）晶面上Pt NPs的动态收缩和消失。结合校正扫描透射电子显微镜（Cs-corrected STEM）和光谱技术，也证实了在CeO（100）晶面上生成了具有平面正方形[PtO]结构的原子分散Pt。再分散和原子控制归因于高温下PtO的高迁移率及其与CeO（100）上平面正方形O位点的强结合。这些认识对于调控原子分散的铂催化剂具有重要意义。
