Fabrication and photocatalytic properties of cationic and anionic S-doped TiO2 nanofibers by electrospinning

Abstract

In present work, S-doped TiO2 nanofibers, with several hundred nanometers in diameter, have been prepared via electrospinning technique using thiourea and CS2 as the sulfur precursors (denoted as UTF and CTF, respectively). The results revealed that sulfur atoms were successfully incorporated into the bulk phase of TiO2 nanofibers. Cationic doping was found with the substitution of Ti4+ by S6+ and TiOS bonds were formed in the UTF sample, but anionic doping was obtained in the CTF sample and OTiS bonds were produced via the S2− substituted for O2−. Meanwhile, evidence showed that chemisorbed SO42− groups were present on the surface of both S-doped samples. Furthermore, S-doping could effectively inhibit the growth of crystalline grain size and obviously increase light absorbance in visible region. The photocatalytic activity of obtained nanofibers was analyzed for the degradation of organic pollutants by visible-light irradiation, and the photocatalytic mechanism was investigated by employing several scavengers for active species. Results showed that photoinduced holes (h+) and chemisorbed hydroxyls (OHads−) on catalyst surface played a vital role in the photocatalysis of UTF system, but photoinduced holes (h+) and electrons (e−) had the nearly equal importance in CTF system.