Reactive sputtering deposition of photocatalytic TiO2 thin films on glass substrates

Titania polycrystalline thin films with high photocatalytic activity were produced by dc reactive magnetron sputtering. X-ray diffraction experiments revealed that the as-deposited films are amorphous and thus unable to deliver an optimum photocatalytic efficiency. By annealing the deposited coatings for 2 h at 500 °C a competitive crystallographic phase growth of anatase and rutile was observed. The anatase titania developed a very high photocatalytic activity. When immersed in a rhodamine B solution and irradiated with ultra-violet light for different periods of time, one could monitor the degradation rate of the dye concentration with time from the decay of its absorption spectra. Several deposition parameters dictate the optimum performance of the titania coatings, such as their relative oxygen and argon partial pressure, cathode current, bias voltage, external magnetic field and post-annealing temperature.