Study on the photocatalysis of F–S co-doped TiO2 prepared using solvothermal method

Fluorine–sulfur (F–S) co-doped TiO2 materials have been prepared using low-temperature solvothermal method, and tested for catalytic activity by the visible light photocatalytic degradation of the Methylene Blue. For comparison, the mono-elemental doped samples, e.g., S- and F-doped TiO2 have also been prepared and tested under the same conditions. The characterization results showed that F–S co-doped TiO2 has a higher photocatalytic activity than that of mono-doped F- and S-doped samples under visible light irradiation. It is believed that the co-doping gives rise to a localized state in the band gap of the oxide and creates active surface oxygen vacancies, both which are responsible for visible light absorption and the promotion of electrons from the localized states to the conduction band. Characterization by electron paramagnetic resonance revealed the presence of a superoxide radical (O2−) which may be mainly responsible for photodegradation of Methylene Blue under visible light.