Promotion of Visible Light Response of Anatase TiO2 by S-F-codoping

Thursday, 18 December 2014
Xiuqin Chen1, Yaling SU2 and Lecheng LEI1, (1)Zhejiang University, Hangzhou, China, (2)Nanjing Institute of Geography & Limnology. Chinese Academy of Science, Nanjing City, China
Understanding the band gap narrowing of anatase TiO2induced by S-F-codoping is attractive and significant for their potential applications in renewable energy by converting sunlight to electricity or fuels.

In this work, we used density functional theory calculations to investigate the electronic structures of anatase TiO2 and further explored the mechanism of band gap narrowing of anatase TiO2 induced by S-F-codoping. It was found the valence and conduction bands of F-doped TiO2, with the doped F concentration of 1.19 %, consisted of the electrons of O2p and Ti3d.The small amount of electrons of F2p didn't change the band gap of TiO2. For S-F-codoped TiO2, with the same S, F concentration of 1.19 %, the upper valence appeared doping states due to additional S-doping, and the transition of S3p to the conduction band was the reason for the redshift of S-F-TiO2 compared with undoped TiO2.Results indicated that the S-F-codoped anatase TiO2is an intrinsic semiconductor with a band gap of 1.80 eV.

Experimental results exhibited a figure-of-merit for photoelectrochemical (PEC) catalysis of S-F-codoped anatase TiO2 in visible light region. The removal efficiency of Acid Orange 7 reached 98.1 % in 180 min under visible light irradiation (I0 = 0.6 mW/cm2, λ>400 nm) with a bias voltage of 0.25 V. The incident photocurrent intensity was about 20.0 μA/cm2measured online by an electrochemical station.