中文摘要：

本文采用基于密度泛函理论的第一性原理方法研究了F掺杂、N掺杂和F+N共掺杂NaNbO3的晶体结构、形成能、电子结构和带边位置。结果表明F、N单掺杂和共掺杂使得NaNbO3的晶格发生畸变，且共掺杂时晶胞体积最大。F掺杂的形成能大大低于N掺杂，共掺杂的形成能低于N掺杂，因而F的引入可增加N的掺杂量。F掺杂在导带底部形成了Nb4d的部分占据态使带隙降低了0.46eV；N掺杂在价带上方形成了部分占据的N2p电子态，使其光吸收扩展到可见光范围；F+N共掺杂消除了F、N单掺杂的部分占据态，且具有较强的氧化还原能力，其很有可能在可见光下催化裂解水。

英文摘要：

The crystal structure,electronic structure,formation energy and relative positions of F-doped,N-doped and F+N codoped NaNbO3were investigated employing the first principle method based on the density functional theory.The study results of the crystal structureindicate the lattice distortion and expansion of F-doped,N-doped and F+N codoped NaNbO3.The formation energy of F+N codoped NaNbO3is lower than that of N-doped NaNbO3,which indicates that the concentration of the N impurity in the host lattice can be enhanced in thepresence of F doping.For F-doped NaNbO3,the low shift of the conduction band is only0.46eV without altering the valence band.While forN-doped NaNbO3,N doping creates a partially occupied impurity band in the band gap of the host due to electron deficiency on N2p levels,which makes the light absorption shift to visible region.The F+N codoping can eliminate the local trapping,which improves the carriermobility.Hence,F+N codoped NaNbO3would be a promising visible-light-driven photocatalyst for water splitting.