Study On Preparation Of Novel Modified TiO₂ Photocatalyst For Photodegradation Of Organic Pollutants

Because of its advantage of chemical stability, anti-corrosion, non-toxic and low cost, TiO2 shows a great promising application in environmental treatment. However, there is still two chanlleges that further research should be taken. On one hand, the relatively wide band gap of TiO2 make itself can only absorb UV light under 387 nm. On the other hand, the high recombination rate of photo generated electrons and holes also limit their further applications. Therefore, approach of highly efficient visible light responsed TiO2 photocatalyst is becoming the most important topic in this field. In this thesis, two approachs were taken to prepare highly efficient visible light responsed TiO2 photocatalyst.In Chapter 2 of this thesis, S-doped and sulfated nanosized TiO2 photocatalysts were prepared by a low-temperature solvothermal method. The obtained samples were characterized by XRD, UV-vis DRS, FT-IR, FTIR-pyridine, XPS, and nitrogen adsorption-desorption methods. Compared with undoped TiO2, the S-doped and sulfated TiO2 photocatalysts exhibited much higher photocatalytic activity for phenol degradation under visible light irradiation. It was revealed that S was not only incorporated into the crystal lattice of TiO2 replacing Ti4+ (as S4+) but also anchored on its surface in the form of SO42-Further study indicated that there are synergistic effects between doped S and anchored SO42-on improving the visible light photocatalytic activity of TiO2.In Chapter 3 of this thesis, Fe-S codoped TiO2 photocatalysts were prepared by a low-temperature solvothermal method. The obtained samples were characterized by XRD,UV-Vis DRS,FT-IR,BET and EPR,XPS. Compared with undoped TiO2 and S doped TiO2 photocatalysts, the Fe-S codoped TiO2 photocatalysts exhibited much higher photocatalytic activity for phenol degradation under visible light irradiation. It was revealed that the band gap of Fe-S codoped TiO2 was obviously decreased, extending the light response of TiO2 into visible light region, and the doped Fe and SO42- anchored on TiO2 surface are favorable for the separation of photo-induced electrons and holes, suppressing the recombination of electrons and holes and consequently promoting the formation of hydroxyl radical.