Recovery of visible-light photocatalytic efficiency of N-doped TiO2 nanoparticulate films

Bare TiO2 and N-doped TiO2 nanoparticulate films in anatase phase were prepared on glass substrates by laser ablation of titanium target in O-2, N-2/O-2 and NH3/N-2/O-2 atmospheres, respectively. The nitrogen dopant concentration increased notably when a small amount of NH3 was added into the N-2/O-2 mixture. The film prepared in NH3/N-2/O-2 exhibited enhanced photoabsorption and photocatalytic ability in the visible-light region as compared with that produced in N-2/O-2. However, for all films, rapid deactivations were observed with operating time, leading to a poor reusability of the catalysts. With a simple and effective approach of mild heat treatment, the photocatalytic efficiency was completely recovered and the reusability of the film was greatly improved. (C) 2007 Elsevier B.V. All rights reserved.