Single-step synthesis of visible-light TiO_(2-x)N_x photocatalyst nanopowder by thermal plasma

摘要

TiO_2 photocatalyst has been shown to effectively decompose various pollutants in gaseous or aqueous phases. The major defect of TiO_2, however, appears to be the large band-gap energy of 3.2 eV that makes the TiO_2 only being excited by UV light. Furthermore, the manufacturing process of TiO_2 strongly influences the purity and surface properties of resulting nanoparticles which subsequently affect the characteristics of TiO_2 photocatalytic reactions. Therefore, there is a need to produce visible-light photocatalyst via novel processes. In this study, nitrogen-doped TiO_2 (i.e., TiO_(2-x)N_x) nanopowders, which have been recognized as effective photocatalysts for band gap narrowing, were synthesized using a transferred DC plasma torch as the heating source. The TiO_(2-x)N_x nanopowders were formed via a single-step thermal process. The formed TiO_(2-x)N_x samples were characterized with TEM, XRD and UV-Vis. The experimental results indicated that the formed TiO_(2-x)N_x nanopowders had a particle size within 5-20 nm. Furthermore, the formed nanopowders were a mixture of the anatase and rutile phase. An evident red-shift in wavelength absorption was also observed. These results revealed that the proposed thermal plasma method successfully fabricated N-doped TiO_2 in a single-step process.