Livraghi Stefano, Paganini Maria Cristina, Giamello Elio, Selloni Annabella, Di Valentin Cristiana, Pacchioni Gianfranco
Dipartimento di Chimica IFM, Università di Torino and NIS Center of Excellence, Via P. Giuria 7, 10125 Torino, Italy.
J Am Chem Soc. 2006 Dec 13;128(49):15666-71. doi: 10.1021/ja064164c.
Nitrogen-doped titanium dioxide (N-TiO2), a photocatalytic material active in visible light, has been investigated by a combined experimental and theoretical approach. The material contains single-atom nitrogen impurities that form either diamagnetic (Nb-) or paramagnetic (Nb*) bulk centers. Both types of Nb centers give rise to localized states in the band gap of the oxide. The relative abundance of these species depends on the oxidation state of the solid, as, upon reduction, electron transfer from Ti3+ ions to Nb* results in the formation of Ti4+ and Nb-. EPR spectra measured under irradiation show that Nb centers are responsible for visible light absorption with promotion of electrons from the band gap localized states to the conduction band or to surface-adsorbed electron scavengers. These results provide a characterization of the electronic states associated with N impurities in TiO2 and, for the first time, a picture of the processes occurring in the solid under irradiation with visible light.
氮掺杂二氧化钛（N-TiO₂）是一种在可见光下具有活性的光催化材料，已通过实验与理论相结合的方法进行了研究。该材料含有单原子氮杂质，这些杂质形成抗磁性（Nb⁻）或顺磁性（Nb*）的体相中心。两种类型的Nb中心都会在氧化物的带隙中产生局域态。这些物种的相对丰度取决于固体的氧化态，因为在还原时，电子从Ti³⁺离子转移到Nb*会导致Ti⁴⁺和Nb⁻的形成。辐照下测得的电子顺磁共振光谱表明，Nb中心负责可见光吸收，促使电子从带隙局域态跃迁到导带或表面吸附的电子清除剂。这些结果提供了与TiO₂中N杂质相关的电子态的表征，并首次呈现了固体在可见光辐照下发生的过程。
