First-principles Study On Anatase TiO₂Codoped With Iron And Nonmetal Elements

Since1972, Fujishima and Honda （Both of them are Japanese）confirmed thephotocatalytic activity of TiO₂, it has attracted much attention due to its cheapness,toxicity, stability and strong photocatalytic activity. TiO₂, as an ideal semiconductormaterialsare, is widely used in solar cell, sewage treatment and other fields. There arethree crystalline phases of TiO₂in nature, they are anatase, brookite and rutile,respectively. Among them, the visible light photocatalytic effect of anatase TiO₂is thebest. Because anatase TiO₂is a wide band gap semiconductor, and having a band gap ofabout3.23eV, corresponding absorption wavelength is about384nm, so it can onlyabsorbs UV light, but UV light only accounts for a small part of the sunlight, having alower utilization of solar energy. This is the primary cause of limiting of TiO₂in thepractical application.In order to improve the absorptive capacity of visible light and the catalytic ability ofTiO₂, scientists have done a lots of study and obtained some achievements. Among them,ion doping is considered to be an effective method to improve the photocatalytic activityof TiO₂.The synergistic reaction of previous metals and non-metals co-doped can beachieved by Fe single-doped in anatase TiO₂,which is because of the multivalent ofFe.But theory and experimental study of synergy reaction by Fe single doped anataseTiO₂can produce synergy reaction of double doping has not yet appeared.In order toenhance synergy reaction of doping system,we use unique advantage of Fe doping andnonmetallic elements.In this aspect,the research of doping system is a shortage.In this paper, based on the density functional theory, using first-principles plate-waveuitrasoft pseudopotential method and the CASTEP （Cambridge Serial Total EnergyParkage） package, a systemic calculation of Fe,C,F,Cl,Br doped anatase TiO₂and Fe/C,Fe/F, Fe/Cl, Fe/Br codoped anatase TiO₂have been presented, and the study proceedwith the following3aspects:（1） In this paper, the calculation of electronic structures and optical properties of3kinds of Fe doping concentration have been presented; In the different doping concentration,a systemic comparison of the band structures, densities of states and the absorptionspectra of Fe doped anatase TiO₂also have been presented, and obtained some useful results. We hope that these results may be helpful for the experimental preparation of Fedoped anatase TiO₂.（2） The calculation of nonmetallic elements elements （C,FCl,Br） single dopedanatase TiO₂electronic structures and optical properties have been presented,andobtained some useful results.（3） Based on the reaearch of Fe elements and nonmetallic elements （C,FCl,Br）single doped TiO₂, we have investigated Fe/C, Fe/F, Fe/Cl, Fe/Br double doped anataseTiO₂by selecting the appropriate element. The electronic structures and optical propertiesof them have been calculated. The scope of the absorption light can be changed by thechange of the band gap.