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

Abstract

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–Cl_x (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.