Yoon Yeohoon, Du Yingge, Garcia Juan C, Zhu Zihua, Wang Zhi-Tao, Petrik Nikolay G, Kimmel Gregory A, Dohnalek Zdenek, Henderson Michael A, Rousseau Roger, Deskins N Aaron, Lyubinetsky Igor
Fundamental and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352 (USA).
Chemphyschem. 2015 Feb 2;16(2):313-21. doi: 10.1002/cphc.201402599. Epub 2014 Oct 30.
By using a combination of scanning tunneling microscopy (STM), density functional theory (DFT), and secondary-ion mass spectroscopy (SIMS), we explored the interplay and relative impact of surface versus subsurface defects on the surface chemistry of rutile TiO2 . STM results show that surface O vacancies (VO ) are virtually absent in the vicinity of positively charged subsurface point defects. This observation is consistent with DFT calculations of the impact of subsurface defect proximity on VO formation energy. To monitor the influence of such lateral anticorrelation on surface redox chemistry, a test reaction of the dissociative adsorption of O2 was employed and was observed to be suppressed around them. DFT results attribute this to a perceived absence of intrinsic (Ti), and likely extrinsic interstitials in the nearest subsurface layer beneath inhibited areas. We also postulate that the entire nearest subsurface region could be devoid of any charged point defects, whereas prevalent surface defects (VO ) are largely responsible for mediation of the redox chemistry at the reduced TiO2 (110).
通过结合使用扫描隧道显微镜（STM）、密度泛函理论（DFT）和二次离子质谱（SIMS），我们探究了表面缺陷与次表面缺陷之间的相互作用以及它们对金红石型TiO₂表面化学的相对影响。STM结果表明，在带正电的次表面点缺陷附近几乎不存在表面氧空位（VO）。这一观察结果与DFT计算得出的次表面缺陷接近度对VO形成能的影响一致。为了监测这种横向反相关对表面氧化还原化学的影响，我们采用了O₂解离吸附的测试反应，并观察到在它们周围该反应受到抑制。DFT结果将此归因于在受抑制区域下方最近的次表面层中不存在本征（Ti）以及可能不存在非本征间隙原子。我们还推测，整个最近的次表面区域可能不存在任何带电点缺陷，而普遍存在的表面缺陷（VO）在很大程度上负责还原态TiO₂（110）上氧化还原化学的介导作用。
