P掺杂锐钛矿相TiO2的第一性原理计算

利用基于密度泛函理论的第一性原理对不同P掺杂形式(P替位Ti, P替位O, 间隙P)的锐钛矿相TiO₂的晶格常数、电荷布居、能带结构、分态密度和吸收光谱进行了计算. 结果表明, P替位Ti时, TiO₂体积减小, P替位O和间隙P的存在使TiO₂的体积膨胀; 替位Ti的P和间隙P均有不同程度的氧化, 而替位O的P带有负电荷. 三种P掺杂形式均导致锐钛矿相TiO₂禁带宽度的增大, 并在TiO₂禁带之内引入了掺杂局域能级. P掺杂导致TiO₂禁带宽度增大的程度依次为: 间隙P>P替位Ti>P替位O. 吸收光谱的计算结果表明, P替位Ti并不能增强TiO₂的可见光吸收能力, 但间隙P的存在大幅提高了TiO₂的可见光光吸收能力, 间隙P有可能是造成实验上P掺杂增强锐钛矿相TiO₂光催化活性的重要原因. 关键词： P掺杂 2')" href="#">锐钛矿相TiO₂ 第一性原理

First-principles calculations of P-doped anatase TiO2

The lattice parameters, charge populations, band structures, density of states and absorption spectra of P-doped anatase TiO₂ are calculated using the first-principles based on the density functional theory. The results indicate that when the Ti atom is substituted for P atom, the volume of TiO₂ decreases. When P atom substitutes for O atom or exists as interstitial atom, the volume of TiO₂ increases. The substitutional P at Ti site and interstitial P are oxidized to different degrees, and the substitutional P at O site is reduced a little. The different three sites of P doping result in the increase of anatase TiO₂ forbidden gap width and the introduction of local doping energy levels. The band gap increasing of P-doped anatase TiO₂ is in the following sequence: interstitial P>substitutional P at Ti site>substitutional P at O site. The absorption spectra indicate that the substitutional P at Ti site cannot enhance the visible light absorption ability of the anatase TiO₂, whereas the interstitial P strongly enhances the visible light absorption ability of the anatase TiO₂. The interstitial P is probably an important reason for the experimental enhancement of the photocatalytic activity of P-doped anatase TiO₂.