Preparation And Visible Photocatalytic Properties Of N-TiO₂/RGO Composites

With the rapid development of society, organic water pollutions become more and more seriously. Photocatalytic degradation of organic pollutions is one of most useful methods to control environment problems. Among semiconductor photocatalytic materials, TiO₂ has been recognized as one of the most promising semiconductor photocatalysts for its chemical stability, high catalytic activity, corrosion resistance, non-toxic, inexpensive, etc. However, TiO₂ has a large band gap?3.2 e V? and can only be actived by ultraviolet light, Moreover, the photogenerated electron-hole pairs easily recombinated, which decrease the utilization rate of photoproduction carrier. These shortcomings greatly limit the application of TiO₂.Aiming at those problems, Through doping of nitrogen and loading of graphene to modify the TiO₂, N-TiO₂, TiO₂/RGO and N-TiO₂/RGO was prepared by mild hydrothermal method without subsequent calcination process respectivaly. The phase, morphology and spectral absorption properties of the as-prepared samples were characterized by XRD, SEM, TEM, XPS, FT-IR, DRS. The photocatalytic performance of the samples was studied by photocatalytic degradation of Methylene Orangeunder under visible light as model reaction.1. The N-TiO₂ was prepared by hydrothermal method using Ti?C4H9O?4 and CO?NH2?2 as precursor with the molar ratio of N/Ti was 0.2, 0.4, 0.6 and 0.8. The results suggested that the anatase phase of TiO₂ was retained by nitrogen doping. However the band gap of TiO₂ was narrowed, which led to response in visible region. Compared with undoped TiO₂, the photocatalytic activity of N-TiO₂ was increased significantly. When the molar ratio of N/Ti was 0.6, the photocatalytic activity was best. it could degrade 70% methyl orange under visible light irradiation in 5 h.2. The TiO₂/RGO was prepared by hydrothermal method using Ti?C4H9O?4 and C as precursor with the mass ratio of RGO was 1 wt%, 2 wt%, 3 wt% and 5 wt%. The results suggested that the anatase phase of TiO₂ was retained by RGO loading, but it could inhibit TiO₂ particles to grow and make it uniformly distributed in the graphene sheet, meanwhile, narrowe the band gap of TiO₂ which lead to response in visible region. Moreover the composite photo-generated electrons and holes was inhibited effectively. Compared with undoped TiO₂, the photocatalytic activity of TiO₂/RGO had been greatly increased. When the mass ratio of RGO was 3wt%, the photocatalytic activity was best. it could degrade 86% methyl orange under visible light irradiation in 5 h.3. The N-TiO₂/RGO was prepared by hydrothermal method using Ti?C4H9O?4, CO?NH2?2 and C as precursor. The results suggested that the anatase phase of TiO₂ was retained by nitrogen doping and RGO loading. Compared with N-TiO₂ and TiO₂/RGO, the degree of red shift and absorption under visible light and the photocatalytic activity of TiO₂ had been greatly increased. When the molar ratio of N/Ti was 0.6 and the hydrothermal reaction temperature was 180 ? and the hydrothermal reaction time was 8h, the photocatalytic activity was best. it could degrade 95% methyl orange under visible light irradiation in 5 h.