Improved visible-light photocatalytic activity of titania activated by nitrogen and indium modification

Nitrogen and indium co-modified TiO2 was prepared by a simple sol–gel method. Under visible-light irradiation, the modified catalysts exhibited much higher photocatalytic activity for 4-chlorophenol photodegradation than both the as-prepared TiO2 and nitrogen-doped TiO2. The structure and properties of the resultant catalysts were characterized by XRD, BET, XPS, UV-vis DRS and PL techniques. It was found that unique chemical species, such as N–O and O–In–Clx (x = 1 or 2), existed on the surface of the nitrogen and indium co-modified TiO2. The surface-state energy levels introduced by these surface species were located close to the valence and conduction bands, respectively, which could lead to significant absorption in the visible-light region and facilitate the separation of photogenerated electrons and holes. Thus, the visible-light photocatalytic activity of TiO2 can be greatly improved by nitrogen and indium modification. We envision the opportunities for using such a method to develop TiO2-based visible-light photocatalysts suitable for practical applications.