Wendt Stefan, Sprunger Phillip T, Lira Estephania, Madsen Georg K H, Li Zheshen, Hansen Jonas Ø, Matthiesen Jesper, Blekinge-Rasmussen Asger, Laegsgaard Erik, Hammer Bjørk, Besenbacher Flemming
Interdisciplinary Nanoscience Center (iNANO), Department of Physics and Astronomy, and Institute for Storage Ring Facilities, University of Aarhus, DK-8000 Aarhus C, Denmark.
Science. 2008 Jun 27;320(5884):1755-9. doi: 10.1126/science.1159846. Epub 2008 Jun 5.
Titanium dioxide (TiO2) has a number of uses in catalysis, photochemistry, and sensing that are linked to the reducibility of the oxide. Usually, bridging oxygen (Obr) vacancies are assumed to cause the Ti3d defect state in the band gap of rutile TiO2(110). From high-resolution scanning tunneling microscopy and photoelectron spectroscopy measurements, we propose that Ti interstitials in the near-surface region may be largely responsible for the defect state in the band gap. We argue that these donor-specific sites play a key role in and may dictate the ensuing surface chemistry, such as providing the electronic charge required for O2 adsorption and dissociation. Specifically, we identified a second O2 dissociation channel that occurs within the Ti troughs in addition to the O2 dissociation channel in O(br) vacancies. Comprehensive density functional theory calculations support these experimental observations.
二氧化钛（TiO₂）在催化、光化学和传感领域有多种用途，这些用途与该氧化物的还原性相关。通常认为，桥连氧（Obr）空位会导致金红石TiO₂(110)带隙中的Ti3d缺陷态。通过高分辨率扫描隧道显微镜和光电子能谱测量，我们提出近表面区域的Ti间隙原子可能在很大程度上导致了带隙中的缺陷态。我们认为这些特定的施主位点在随后的表面化学中起关键作用，并且可能决定表面化学过程，例如提供O₂吸附和解离所需的电子电荷。具体而言，我们发现除了O(br)空位中的O₂解离通道外，在Ti槽内还存在第二个O₂解离通道。综合密度泛函理论计算支持了这些实验观察结果。
