采用基于密度泛函理论的第一性原理计算方法,对掺杂Fe和(或)V的金红石型TiO2的电子结构进行了计算.理论模拟的结果表明,纯金红石的禁带宽度为1.98 eV;Fe掺杂金红石型TiO2的禁带宽度为2.18 eV,由Fe3d 和O2p轨道杂化在禁带中间形成了两条杂质能级；V掺杂金红石型TiO2的禁带宽度减小为1.80 eV,由V3d和O2p轨道杂化形成的杂质能级位于金红石的导带底,引入了一个浅施主能级；Fe和V共掺杂的金红石禁带中存在一个较宽的杂质能带,禁带宽度减小为1.73 eV.杂质能级的出现以及禁带宽度的减小使得Fe和V掺杂的金红石具有更好的可见光响应能力.同时,Fe和V的类质同像替代使得金红石中MO6八面体具有较大的畸变程度,有助于表面缺陷的增加,从而为光催化反应提供天然活性位.为进一步深入揭示含铁、钒等杂质的天然金红石的可见光催化机制提供了理论支持.%In this study, the electronic structures of Fe- and/or V-doped rutile TiO2 have been investigated using the first-principles calculations based on the density functional theory. Theoretical results show that the band gap of pure rutile is 1.98 eV. The top of the valence band is mainly formed by O2p and Ti3d states, in which O2p state plays a major role, while the conduction band is dominated by Ti3d state. In the calculations of doped models, a 2 × 2 × 2 super-cell structure (Ti16O32) is built based on the optimized geometric parameters of rutile. One Ti atom is replaced by a Fe or V atom with a doping amount of 6.25 %. Fe and V are used to substitute the two nearest-neighbor Ti atoms parallel to the c-axis respectively so as to form the co-doped rutile with a doping quantity of 12.5%. The results show that Fe-doped rutile TiO2 has a band gap of 2.18 eV, and the hybridization of Fe3d and O2p orbital introduce two intermediate bands in the middle of the forbidden band. The band gap of V-doped rutile is reduced to 1.80 eV and the intermediate state right below the bottom of the conduction band is attributed to the hybridization of V3d and O2p orbital, which acts as a shallow donor level. Fe- and V-codoping reduces the band gap of rutile to 1.73 eV and introduces a wide intermediate band into the forbidden gap. The emergence of the intermediate state and the decrease of the band gap make Fe- and V-codoped rutile possess a better responding capability to visible light. Meanwhile, isomorphous substitution of Fe or V atoms for Ti causes significant distortion to MO6 octahedra, which could increase the concentration of surface defects, and thereby provide active sites for photocatalysis. These results supply theoretical aids to profound understanding of the photo-catalytic mechanism of Fe- and V-bearing natural rutile under visible light.
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