Center for Quantum Sciences and School of Physics , Northeast Normal University , Changchun 130117 , China.
Center for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Educations , Northeast Normal University , Changchun 130024 , China.
Inorg Chem. 2019 Mar 4;58(5):3090-3098. doi: 10.1021/acs.inorgchem.8b03096. Epub 2019 Feb 21.
The structural and electronic properties of Nb-doped rutile TiO with several doping configurations were investigated by first-principles calculations based on the density functional theory. The calculations show that although the band gap in the Nb, 2Nb, and Nb + O systems is small, the intragap states would be the electron-hole recombination center, leading to low photocatalytic efficiency. However, for the 2Nb + O configuration, the impurity states are mainly located at the top of the valence band and the electron-hole recombination would be inhibited, indicating relatively higher photocatalytic efficiency. On the basis of the charge-compensated theory, two electrons on the transition-metal Nb atoms compensate for the same amount of holes on the acceptor level of a nonmetal interstitial O atom, in the model of 2Nb + O. Such donor-acceptor codoping may not only suppress the electron-hole recombination but also maintain a reduced band gap, suggesting that the doping models would exhibit higher photocatalytic activity than pure TiO. The calculation results show that the interstitial O atoms play an essential role in manipulating the valence state of impurity Nb. The role of the interstitial O atom in Nb-doped rutile TiO suggests that it can give rise to beneficial charge-compensation effects.
采用基于密度泛函理论的第一性原理计算方法，研究了几种掺杂构型的 Nb 掺杂金红石 TiO 的结构和电子性质。计算表明，尽管 Nb、2Nb 和 Nb+O 体系的带隙较小，但能隙态将成为电子-空穴复合中心，导致光催化效率低。然而，对于 2Nb+O 构型，杂质态主要位于价带顶部，电子-空穴复合会受到抑制，表明具有相对较高的光催化效率。基于电荷补偿理论，在 2Nb+O 模型中，过渡金属 Nb 原子上的两个电子补偿非金属间隙 O 原子受主能级上相同数量的空穴。这种施主-受主共掺杂不仅可以抑制电子-空穴复合，还可以保持较小的带隙，表明掺杂模型比纯 TiO 具有更高的光催化活性。计算结果表明，间隙 O 原子在操纵杂质 Nb 的价态方面起着重要作用。间隙 O 原子在 Nb 掺杂金红石 TiO 中的作用表明，它可以产生有益的电荷补偿效应。
