Preparation And Photocatalytic Properties Of Ag And N Co-Doped TiO₂ Nanotubes

Nowadays, energy shortage and environmental pollution have become the two major problems which threaten our survival and development. Titanium dioxide(TiO2) as a kind of excellent semiconductor materials, has potential in app;ication in the field of solar energy, biological medicine, sewage disposal as well as air purification and other fields. But its band gap is so wide(3.2eV) that it only responses to ultraviolet light, and UV light accounts for only 4% of the sunlight; Meanwhile, the electron hole pair of TiO2 generated by photoexcitation is easy composite. These shortcomings have limited the application of TiO2.However, the above two problems can be solved by using special morphology of TiO2 and doping modification of TiO2.In this paper, TiO2 nanotubes were prepared by magnetron sputtering and anodic oxidation on titanium substrate. N doping and Ag, N co-doping on the TiO2 nanotubes were studied. The structure, morphology, and optical properties of TiO2 nanotubes by using X-ray diffraction(XRD), scanning electron microscopy(SEM), energy spectrum(EDS), transmission electron microscope(TEM), X-ray photoelectron energy spectrum(XPS), and ultraviolet-visible light photometric meter(UV-vis), Then the photocatalytic performance of Ndoping and Ag, N co-doping on TiO2 nanotubes by degrading methyl orange as organic pollutants under visible light. The results are as follows:The XRD result shows that TiO2 nanotubes is composed of anatase phase;SEM and EDS results imply that TiO2 nanotubes grow independently and its nozzle do not collapse; nanotube length is about 2 μm, diameter is about 40 nm,tube wall is about 15 nm.N was doped into TiO2 nanotubes and then the influence on photocatalytic of TiO2 nanotube was studied under different amounts of N. The results show that the doping of N on TiO2 nanotubes has little effect on its morphology and structure. Compared with pure TiO2 nanotubes, the visible light absorption band of N doping TiO2 nanotubes occur red shift, and the visible absorption intensity and photocatalytic performance have improved obviously; meanwhile, with the increase of volume flow rate ratio of Ar2 and N2, the light absorption and photocatalytic performance appeare the trend of first crease then decrease, When the volume flow rate ratio of Ar2 and N2 is 70:1 the visible light absorption and photocatalytic performance is strongest, the photodegredation rate can reach47%. This is because that the doping of N forms intermediate energy levels,which promotes the electronic transition, meanwhile, the holes on the energy levels are more likely to form hydroxyl radicals, which can improve the photocatalytic activity.Ag, N co-doping TiO2 nanotubes also was studied and then and then the influence on photocatalytic of TiO2 nanotube was studied under differentamounts of Ag. The ruselts imply that Ag, N co-doping has no significant effect on the morphology of TiO2 nanotubes. The incorporation of Ag promotes the phase transformation of TiO2 nanotube, whose crystal structure is composed of anatase and rutile hybrid; The light absorption of Ag, N co-doped TiO2 nanotube has red shift, visible light absorption intensity and light catalytic performance are more stronger than that of N-doped TiO2 and pure TiO2 nanotubes. and with the doping amount of Ag increasing, light absorption and light catalytic performance showed a trend of first increased and then decreased, the catalytic properties of TiO2 nanotubes are the strongest in 20 s Ag, N co-doped, and the photodegredation rate can reach 63%. This is because that the co-doping of Ag,N can form the impurity level, and reduce the TiO2 band gap; on the other hand,Ag doping can inhibit the recombination of electron hole pairs.