Abstract: 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 .

Key words: 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 .