Ab initio modeling of sulphur doped TiO2 nanotubular photocatalyst for water-splitting hydrogen generation

In order to construct an efficient visible-light-driven TiO2 photocatalyst for water splitting applications, one has to perform improvements of its electronic structure. In this theoretical study we consider single-walled anatase TiO2 nanotubes having following morphologies: (101) 3-layered wall with chirality indexes (n, 0) and (n, n), (101) 6-layered wall with (n, 0) and (0, n), (001) 6-layered wall with (n, 0) and (0, n), and (001) 9-layered wall with (n, 0) and (0, n). The latter configuration occurs to be the most energetically stable, due to possessing negative strain energy. In our study the most stable 9-layered anatase (001) (0, n) nanotube has been doped with sulphur. According to obtained results sulphur dopant creates the mid-gap states making the TiO2 nanotube to be a good candidate for efficient photocatalyst working under day light irradiation.