氮掺杂对锐钛矿相TiO_(2)的电子结构及光学性质的影响研究

Study of electronic structures and optical properties of N-doped anatase TiO_(2)

通过氮原子取代不同位置的Ti或者O原子,构建了三种不同掺杂结构的氮掺杂TiO_(2):O-Ti-N、Ti-O-N和N-Ti-N。基于密度泛函理论,第一性原理计算研究了三种氮掺杂结构对于TiO_(2)的晶体结构、能带结构、态密度和光学性质的影响。研究结果表明:三种掺杂结构都可以稳定地存在于TiO_(2)中,符合文献报道。氮原子的掺杂显著降低了TiO_(2)的禁带宽度。由于N 2p和O 2p之间的杂化作用,在禁带区域形成杂质能级,降低了激发电子向导带跃迁所需的能量。Ti-O-N掺杂结构的TiO_(2)吸收光谱发生了明显的红移现象,说明该结构更有利于提高TiO_(2)在可见光范围的光催化活性。

By substituting N atoms for Ti or O atoms at different positions,three doped structures at different positions are constructed,i.e.,O-Ti-N,Ti-O-N and N-Ti-N.Based on density functional theory and first-principles calculations,the effects of three kinds of nitrogen doping on the crystal structure,energy band structure,density of states and optical properties of TiO_(2) were studied.The research results show that all three doped structures can be stably existed in TiO_(2).The doping of nitrogen atoms significantly reduces the band gap of TiO_(2).Due to the hybridization between N 2p and O 2p,impurity levels are formed in the forbidden band region,which reduces the energy required to excite the electron to conduction band.In the Ti-O-N structure,the absorption spectrum shows obvious red shift,which proves that this structure is more conducive to improving the photocatalytic activity of TiO_(2) in the visible light range.