Modified Graphene/Nitrogen Doped Titania Hybrid Materials,Preparation And The Study Of Photocatalytic Activity

With the development of social industrialization, organic pollutions become more and more seriously, which come from people’s daily life and industrial production. Photocatalytic degradation of organic pollutions is one of most useful methods to control environment problems. There are many photocatalyst such as ZnO, NiO, CdS, TiO2. TiO2is the most common photocatalyst which has low cost, high photocatalytic activity, good stability and many other advantages. However, it also has some disadvantages such as wide band gap, low separation efficiency of electron-hole pairs, which greatly limit the photocatalytic applications of TiO2.In order to overcome these problems, nitrogen and graphene were doped into TiO2. Nitrogen doping can effectively reduce the band gap of TiO2, and increase the absorption of visible light. As Graphene has high specific surface area and excellent electronic conductivity, graphene can serve as supported materials and fast transfer electrons to the surface of TiO2, so it can restrict the recombination of electron-hole pairs and improve the photocatalytic degradation efficiency of the hybrid materials.In this paper, nitrogen-doped TiO2(NT) using ethylenediamine as the source of nitrogen was firstly prepared. Then, NT was composited with graphene oxide (GO), nitrogen doped grapheme (NG) and nitrogen doped graphene synthsised by small molecules (NSG) respectively. And the corresponding haybrid materials were named as G-NT, NG-NT and NSG-NT. The structures, morphology and optical properties were characterized by FT-IR, XRD, XPS, AFM, TEM, and UV-Vis DRS. XPS results demonstrated that element nitrogen was susessfully doped into crystal lattice of TiO2, and replaced part of element oxygen. UV-Vis DRS spectra indicated the light adsorption of TiO2can be extended to visible light region by doping nitrogen, and the light adsorption of NT can be further improved by doping NG. The band gap of P25, NT, G-NT, NG-NT and NSG-NT calculated from UV-Vis DRS spectra are3.14,2.97,2.97,2.74and2.93eV respectively. The band gap of NG-NT is0.4eV lower than that of NT, which suggested that the band gap of catalysts can be effectively reduced by doping nitrogen. Using above prepared hybrid materials as photocatalyst and methylene blue as organic pollutant, photocatalytic degradation experiments were carried out under the same conditions. After3hours, the degradation efficiency of methylene blue by P25, NT, G-NT, NG-NT and NSG-NT were16%,20%,33%,63%and52%respectively. Photocatalytic efficiency by G-NT is1.65times that of NT, the photocatalytic activity was enhanced greatly by doping graphene into TiO2. Photocatalytic efficiency by NG-NT is1.91times that of G-NT and3.15times that of NT. Photocatalytic efficiency by NSG-NT is2.6times that of NT.