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 O2, N2/O2 and NH3/N2/O2 atmospheres, respectively. The nitrogen dopant concentration increased notably when a small amount of NH3 was added into the N2/O2 mixture. The film prepared in NH3/N2/O2 exhibited enhanced photoabsorption and photocatalytic ability in the visible-light region as compared with that produced in N2/O2. 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.