External electric and magnetic fields enhanced photocatalytic efficiency of TiO2 nanoparticulate films prepared by sparking process

Abstract Nitrogen (N)-doped anatase/rutile TiO2 nanoparticulate (NP) films were successfully prepared by a sparking process under external electric (E) and magnetic (B) fields without heat treatment. As-deposited NP films annealed at 250 °C, 350 °C, and 450 °C prepared by the sparking process without E and B fields were compared with as-deposited NP films prepared with E + B fields. The results clearly show that the quantity of the NP films increases after sparking under E and B fields. Interestingly, sparking under E + B fields can enhance both the film crystallinity and photocatalytic efficiency. Furthermore, N-doped TiO2 was observed only in NP films prepared by sparking under E + B fields. Doping with N not only plays an important role in enhancing the photocatalytic activity but also manipulates the spin polarization of TiO2 under E + B fields to enhance the film crystallinity and photocatalytic efficiency without the need for an annealing system.