First principles study of nitrogen doping at the anatase TiO2(101) surface
First principles study of nitrogen doping at the anatase TiO2(101) surface
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DOI：
10.1021/jp071186s
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发表时间：
2007-07-05
影响因子：
3.7
通讯作者：
Pacchioni, Gianfranco
中科院分区：
文献类型：
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作者：
Finazzi, Emanuele;Di Valentin, Cristiana;Pacchioni, Gianfranco
采用第一性原理密度泛函理论研究了氮杂质在TiO2（101）表面的掺杂.几个替代和填隙配置和不同浓度的N杂质在表面和次表面层，以及它们与氧空位在TiO 2晶格中的相互作用。各种研究系统的稳定性进行比较的基础上，它们的形成能作为一个功能的氧化学势，这决定了该系统是在氧化或还原环境。在富氧条件下，结合到表面O的N是优选的，而在贫氧条件下，取代N连同氧空位是有利的，如先前发现的体TiO 2。在次表层中存在N杂质的情况下，形成表面氧空位的成本几乎被取消。在晶格中掺入氮通过在带隙中引入局域态来修改电子结构，这与在可见光区中实验观察到的N掺杂的ZnO样品的吸收一致。此外，这些N杂质态是来自表面氧空位的Ti 3+电子的优良陷阱。计算了不同N掺杂的SiO_2（101）表面模型的STM图像，为今后该表面的实验研究提供参考。
The incorporation of nitrogen impurities in the anatase TiO2(101) surface is investigated by first principles density functional theory calculations. Several substitutional and interstitial configurations and different concentrations for the N impurities in the surface and subsurface layers are considered, as well as their interactions with oxygen vacancies in the TiO2 lattice. The stability of the various investigated systems is compared on the basis of their formation energy as a function of the oxygen chemical potential, which determines whether the system is in an oxidizing or reducing environment. Under oxygen-rich conditions, N bound to a surface O is preferred, whereas, under oxygen-poor conditions, substitutional N together with oxygen vacancies is favored, as previously found for bulk TiO2. The cost of formation of a surface oxygen vacancy is almost cancelled in the presence of N impurities in subsurface layers. The incorporation of nitrogen in the lattice modifies the electronic structure by introducing localized states in the band gap, consistent with the experimentally observed absorption of N-doped anatase samples in the visible region. Also, these N impurity states are excellent traps for the Ti3+ electrons deriving from surface oxygens vacancies. STM images for the various N-doped anatase (101) surface models have been computed to provide a reference to future experimental studies of this surface.