(Nb,N)共掺杂锐钛矿电子结构和光学性质的第一性原理研究
- 武汉大学物理科学与技术学院,武汉,430072
- 武汉科技大学材料与冶金学院,武汉,430000
摘要: 二氧化钛(TiO2)作为一种性能优良的光催化剂已经受到越来越多的关注.本研究采用密度泛函理论的第一性原理和广义梯度近似+U方法,对锐钛矿结构Ti02晶体三种可能的(Nb,N)共掺杂Ti02的几何结构、形成能、能带结构、电子密度和光吸收系数进行了研究,并与单掺杂(Nb/N)体系进行了对比.对掺杂后体系的几何结构进行的计算表明杂质原子掺入后晶格发生了不同程度的畸变.此外,(Nb,N)共掺杂体系与纯TiO2相比,其禁带宽度和吸收边较小.同时,与N掺杂TiO2相比,N的2p态在共掺杂情形下变为完全占据,从而减少了电子空穴对的复合.而且共掺杂体系的形成能比N单掺杂体系低,因而更加稳定.因此,(Nb,N)共掺杂可以很好地提升锐钛矿型Ti02在可见光波段的光催化性能.
First principles calculations of the electronic structure and optical properties of pure and (Nb, N) co-doped anatase
- 武汉大学物理科学与技术学院,武汉,430072
- 武汉科技大学材料与冶金学院,武汉,430000
Keywords:
- 电子结构 /
- 密度泛函理论 /
- 锐钛矿 /
- 共掺杂
Abstract: Titanium dioxide (TiO2), as a kind of excellent photocatalyst, has been widely researched and applied. The geometry structures, band structures, densities of states and absorption coefficients of three possible (Nb, N) co-doped anatase are studied by the density functional theory based on GGA+U method, and the results are compared with those of the single doped (Nb/N) anatase. It is shown that the introduction of dopants leads to the lattice distortion. Besides, compared with undoped TiO2, (Nb, N) co-doped TiO2 has small band gap and absorption edge, and the level of N 2p state changes from partially occupied to occupied, which reduces the recombination of electron-hole pairs. In addition, the smaller formation energy of co-doped anatase indicates that it is more stable than the N doped anatase. Therefore, (Nb, N) co-doping anatase is a kind of stable photocatalyst and it has better photocatalytic performance in visible light band than pure TiO2.