Because of the anatase ' s broad eg ( 3 . 2ev ) , the absorption thresholds correspond to 380nm for the tio2 . consequently , only the ultraviolet fraction of the solar irradiation can be active in the photoexcitation processes using pure tio2 solid . the high recombination rate of charge carrier and low efficiency of quantization are also the deficiencies of pure tio2 由于tio _ 2的带隙较宽(约3 . 2ev ) ，半导体的光吸收波长范围窄(主要在紫外区) ，故其太阳能的利用效率低，且还存在半导体载流子的复合率高，量子化效率低等缺陷。
