Zhang Yajun, Xu Zhongfei, Li Guiyu, Huang Xiaojuan, Hao Weichang, Bi Yingpu
State Key Laboratory for Oxo Synthesis & Selective Oxidation, National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, CAS, Lanzhou, 730000, P. R. China.
Department of Physics, Beihang University, Beijing, 100191, P. R. China.
Angew Chem Int Ed Engl. 2019 Oct 1;58(40):14229-14233. doi: 10.1002/anie.201907954. Epub 2019 Aug 29.
Oxygen vacancy (Vo) on transition metal oxides plays a crucial role in determining their chemical/physical properties. Conversely, the capability to directly detect the changing process of oxygen vacancies (Vos) will be important to realize their full potentials in the related fields. Herein, with a novel synchronous illumination X-ray photoelectron spectroscopy (SI-XPS) technique, we found that the surface Vos (surf-Vos) exhibit a strong selectivity for binding with the water molecules, and sequentially capture an oxygen atom to achieve the anisotropic self-healing of surface lattice oxygen. After this self-healing process, the survived subsurface Vos (sub-Vos) promote the charge excitation from Ti to O atoms due to the enriched electron located on low-coordinated Ti sites. However, the excessive sub-Vos would block the charge separation and transfer to TiO surfaces resulted from the destroyed atomic structures. These findings open a new pathway to explore the dynamic changes of Vos and their roles on catalytic properties, not only in metal oxides, but in crystalline materials more generally.
过渡金属氧化物上的氧空位（Vo）在决定其化学/物理性质方面起着关键作用。相反，直接检测氧空位（Vos）变化过程的能力对于在相关领域充分发挥其潜力至关重要。在此，通过一种新型的同步照明X射线光电子能谱（SI-XPS）技术，我们发现表面Vos（surf-Vos）对与水分子结合表现出很强的选择性，并依次捕获一个氧原子以实现表面晶格氧的各向异性自修复。在这个自修复过程之后，幸存的次表面Vos（sub-Vos）由于位于低配位Ti位点上的电子富集，促进了电荷从Ti原子激发到O原子。然而，过多的sub-Vos会由于原子结构的破坏而阻碍电荷分离并转移到TiO表面。这些发现为探索Vos的动态变化及其在催化性能方面的作用开辟了一条新途径，不仅适用于金属氧化物，更普遍地适用于晶体材料。
