O、Se和Te掺杂对单层MoS2电子能带结构和光学性质的影响

利用密度泛函理论第一性原理,计算了本征单层MoS2以及O、Se和Te掺杂单层MoS2的结构参数、能带结构、氧化还原电势、态密度、光吸收特性和光催化潜力.结果表明,本征和掺杂单层MoS2的晶胞参数、键长随原子半径的增大而增大,键角随原子半径的增大而减小.掺杂后禁带宽度变小,导电性增强.本征和掺杂的单层MoS2的导带底电位负于水解制氢反应的还原势,其价带顶电位正于水解制氢反应的氧化势,均具有光催化水解制氢的潜力.但是,本征和O掺杂,由于价带顶与导带底电位相应于水的氧化还原势和电子空穴需求量均存在不平衡,使其光解水性能不理想.然而,Se和Te掺杂可以平衡其还原与氧化能力,改善单层MoS2的光催化的性能,其中Se掺杂改善效果最为明显.同时,掺杂后的单层MoS2对可见光吸收效率增强.此研究有助于筛选合适的单层MoS2掺杂元素,提高单层MoS2材料的光催化水解制氢性能.

Effect of O,Se and Te Doping on the Electronic Band Structure and Optical Properties of Single Layer MoS2

Based on the first principles method of density-functional theory , structural parameters , band structures , redox potentials , density of states , light absorption properties and photocatalysis potential of both pure and O, Se and Te doping single-layer MoS2 were calculated.The results indicate that the lattice parameter and bond length of pure and doped single-layer MoS2 increase with the increase of atomic radius , and the bond angle decrease with atomic radius increasing .The band gap becomes smaller and electrical conductivity become stronger after doping .Pure and doped single-layer MoS2 both have potential as photocatalyst in water splitting .Because the bottom edge of the conduction band is higher than the reduction potential of H 2 O/H2 , and the top edge of the valence band is lower than the oxidation potential of O2/H2 O.However, pure and O-doping single-layer MoS2 have low photocatalytic efficiency due to a extreme imbalance of redox potentials with electron-hole demand .After Se and Te doping , dopped single-layer MoS2 have higher photocatalytic capacity by equilibrating redox potentials and electron-hole demands. Meanwhile, the dopped single-layer MoS2 have better optical absorption , especially for visible light absorption .This research give a helpful support to screen the suitable doping for single-layer MoS2 , and to improve the performance of photocatalytic water splitting .