Comparison of anatase and rutile for photocatalytic application: the short review

The dioxide titanium (TiO2) is attracting a great attention as semiconductor photocatalyst because of its high photoreactivity, non-toxicity, corrosion resistance, photostability, cheapness. It can be used in wide range of applications: air and water purification, hydrogen (H-2) generation, CO2 reduction, in photovoltaic application and others. The efforts of scientists were applied to use solar light for dioxide titanium photocatalysis and to enhance the photocatalytic efficiency. In this article we review the properties difference of anatase and rutile modifications of TiO2. The anatase has a higher photoefficiency. The higher photoefficiency of anatase is due to longer lifetime of charge carriers (lifetime of e(-)/h(+) in anatase on 3 order higher than in rutile). But anatase has higher band gap energy (3.2 eV or 388 nm) in comparison with rutile (3.0 eV or 414 nm). Thus, anatase becomes photosensitive in ultraviolet (UV) diapason of light, meanwhile rutile - in violet spectrum of visible light. It is desirable to obtain TiO2 semiconductor with properties combining best ones from anatase and rutile: higher photoreactivity and smaller band gap. It can be made by using external factors such as electric or magnetic fields, doping and etc.