Study of electronic structures and optical properties of N-doped anatase TiO2
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摘要: 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TiO2: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TiO2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TiO2中,符合文献报道。氮原子的掺杂显著降低了TiO2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TiO2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TiO2在可见光范围的光催化活性。Abstract: 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 TiO2 were studied. The research results show that all three doped structures can be stably existed in TiO2. The doping of nitrogen atoms significantly reduces the band gap of TiO2. 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 TiO2 in the visible light range.
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Key words:
- N-doped TiO2 /
- energy band structure /
- density of state /
- optical properties
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表 1 TiO2和氮元素掺杂TiO2优化后的晶胞参数和总能量
Table 1. Optimized unit cell parameters and total energy of pure TiO2 and N-doped TiO2
类型 a/nm b/nm c/nm V/nm3 E0/eV TiO2 0.778710 0.778710 0.978800 0.593533794 −365.54086917 O-Ti-N 0.781097 0.778549 0.978708 0.595174387 −363.54055310 Ti-O-N 0.777451 0.777451 0.971251 0.587052397 −353.11233872 N-Ti-N 0.782302 0.778209 0.981618 0.597601365 −361.82706653 -
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