4. Conclusion
In summary, we have systematically studied the TiOS doped by all 4d TM
atoms. New impurity energy bands can be generated in the bandgap and the
semiconductor-metal phase transition can be induced by dopings. The
visible-light absorption can be seriously increased by doping Y, Zr, Nb,
Mo, and Ag, and only weakly increased by doping other 4d TM atoms. The
former should be caused by both interband and intraband transitions of
electrons while the latter should be only the interband transition.
Furthermore, we discussed the doping-induced improvement of the
photocatalytic activities of TiOS. It is verified that among all 4d TM
atoms both Y and Ag dopings can be used to effectively improve the
visible-light photocatalytic activities of the TiOS.