Study On The Electronic Structure Of TiO₂

TiO₂,as the best photocatalyst material, has most widely application prospects atpresent because of its many virtues such as good stability, high efficiency, resistanceto corrosion, non-toxic, no-pollution, and low cost and many other advantages. Butfor its wider band gap, TiO₂has low visible light utilization rate in the photocatalyticprocess. Therefore, the method of doping is applied widely to improve visibleutilization. However, the doping test is more complex and has higher equipmentrequirements. Therefore, this paper studies the effects of nonmetal doped, metaldoped and metal-Nonmetal double-doped on the band energy structure, state densityand photocatalysis properties of TiO₂by using first-principles. The results are asfollows:The top of the valence band of rutile and anatase phase, which are two kinds oflattice type of TiO₂, is composed of O2p orbit, and the conduction band bottom iscomposed of Ti3d.Anatase TiO₂is2.04eV, rutile TiO₂is1.846eV.The redshift ofrutile TiO₂is smaller than that of anatase TiO₂, indicating that the anatase TiO₂photocatalytic efficiency is better than that of the rutile phase.Through the establishment of doping model, the energy band structure of non-metallic elements B, C, N, F, S, P with TiO₂doped is calculated, the light absorptioncurve data is obtained. When the anatase TiO₂is doped with these non-metallicelements, redshift degree order is as follows: P> C> N> S> pure TiO₂> B> F.When the anatase TiO₂is doped with Ag, Co, Fe, Cr, Ni, Mn, redshift degreeorder is as follows: Ag> Co> Fe> pure TiO₂≈Cr> Ni> Mn. The authors come tothe law that the redshift produced by light absorption is in inverse proportion to thegap width of element doped TiO₂.Comparing the metal doped TiO₂and nonmetal doped TiO₂above, the dopingredshift degree order is as follows: P> Ag> C> N> S> Co> Fe> pure TiO₂≈Cr>Ni> Mn> B> F.The co-doping of Ag and P has better photocatalytic effect than that of Ag or P;and the co-doping of Fe and S has worse photocatalytic effect than Fe or S; the photocatalytic effect of the co-doping of Ag and C is worse than Ag, but better than P.