Study Of Electronic Structure And Optical Properties On Double Impurities Doping Of Anatase TiO₂

TiO₂, titanium dioxide, white is widely used in coatings, plastics, cosmetics and other industries. Since the 70 s, in view of the scientific study has found that titanium dioxide, titanium dioxide with good optical, electrical, magnetic, and electrochemical properties. Due to its mild properties stable, low consumption, in the field of organic pollutant degradation, water decomposition has huge potential application. But the titanium dioxide as photocatalyst, its forbidden band width is wide, can only be larger optical excitation frequency, low utilization ratio of visible light. So to doping of TiO₂ anatase phase, make its electronic structure and optical properties change, expand its use in the field of light catalysis and photoelectric conversion are hot topics in the study of many scholars. With nonmetallic element doped TiO₂ as a starting point, after doping forbidden band width of TiO₂ is reduced, the absorption spectrum and reflection spectrum redshift, significantly improve the efficiency of titanium dioxide to visible light. After that, the researchers tried metal elements doping, rare earth element doped with a variety of ways. In this paper, we study the double the effects of impurity doped TiO₂ anatase phase.Based on first principles, based on density functional theory of plane wave super soft constraint potential method, this paper calculated the doping modification of TiO₂ anatase phase crystal structure and band and state density, density of states and optical properties change, research ideas and conclusions are as follows:（1） build a non-metallic impurities double mixing model, with a C-N, C-S, N-S codoping as an example, the calculation and analysis of the band of TiO₂ anatase phase after doping crystal, state density, density of states and optical properties of change. Investigation of non-metallic impurities mixed pairs can improve TiO₂ photocatalysis effect. Results show that the doping method effectively reduced the forbidden band width of TiO₂, and generate the impurity level, reduce the electrons from the valence band to the conduction band energy transition.（2）Non-metallic elements N and to calculate the 3 d transition state metals Cr, Cu doped TiO₂, respectively with a substitution O N atoms, metal atoms to replace Ti, build N- Cr, N- Cu double impurities codoping TiO₂ model. For calculation of electronic structure and optical properties of the results can be seen, N, N- Cr- Cu synergy, metallic and non-metallic elements, the mixed N formed a new impurity level, 3 d metal electron orbital formed after doping the contribution of the local level, so as to improve the utilization of anatase type titanium dioxide to visible light.（3） are calculated and analyzed the bimetallic element doped TiO₂ crystal after modification. In 3 d transition state of metal Cr and Cu, for example, choose a suitable location with TiO₂, according to the band structure after doping found that impurity level, forbidden band width is reduced, high-energy zone and low-energy OuDeGuang visible light absorption and reflection efficiency were improved to a certain extent, visible, double metal impurities mixed also enhanced the photocatalytic activity of TiO₂.（4） in order to further determine the effect of two impurities for codoping titanium dioxide modified, non-metallic impurities doped double elements, for example, this paper also studied the nature of the change after the crystal doped TiO₂ rutile phase. C- N, C, S, N- S codoping as the research object, and anatase TiO₂ crystal modification conditions were compared. Analysis, from which a form of titanium dioxide, double doped impurity can influence its electronic structure, improve its photocatalytic performance, cause visible absorption redshifts.Thus, double impurities codoping anatase TiO₂ crystal phase change of its electronic structure and optical properties has a positive effect, light absorption redshifts, photocatalytic performance improved, therefore, can be used as ideal photocatalytic materials.