Hf／Ta／W单掺锐钛矿相TiO2的电子结构和光学性质的第一性原理研究

First-principles Study on the Electronic Structure and Optical Properties of Hf/Ta/W Doped Anatase TiO_2

运用第一性原理赝势方法计算过渡金属X(Hf、Ta、W)单掺锐钛矿相TiO_2后的电子能带结构、态密度和光学性质。计算结果表明,X掺锐钛矿相TiO_2,使得掺杂后体系的体积增大,并随着X掺杂浓度的增加而增大;掺杂体系的禁带宽度都比纯TiO_2的要小;由能带图可知,Ta、W单掺后,费米能级进入导带,说明这两种单掺体系属于N型半导体;随着不同浓度Hf、Ta、W的掺入,发现吸收光谱都发生了不同程度的红移,其中Ta、W掺杂体系的光响应范围覆盖了整个可见光区域,对比所有掺杂体系发现Ti_(0. 9375)W_(0. 0833)O_2在可见光区域的光响应能力最强,这些现象说明X的掺入大大提升了TiO_2光催化能力。

The band structures, electronic density of states and optical properties of Hf-doped, Ta-doped, and W-doped TiO2 systems are computed by the first-principles based on density functional theory. The results show that the impurity leads tolargen the doped systems volumeas the impurity concentration increases. The doped systemsbandgap is less than that of pure TiO2. From the band structure graphs of the Ta-doped, and W-doped TiO2 systems,it is found that the bottom of conduction band is under the Fermi level, as is known that the two kinds of doped systems are N-type semiconductor. With the various concentrations of Hf/Ta/W being doped in the TiO2 systems, the absorption spectrums of all the doped systems exhibitvarying degrees of red shift, and the light response range of Ta-doped, and W-doped TiO2 systems covers the entire visible area. Especially, the light responsiveness of Ti0.9375 W0.0833 O2in the visible region is the strongest. In a word, the impurity atoms （Hf, Ta, W） doped greatly improves the photocatalysis of the Anatase TiO2.