Photocatalytic degradation of acetone by Ni-doped titania thin films prepared by dc reactive sputtering

Two series of titania-based photocatalysts were prepared by the sputtering method, in Ar/H2O atmosphere, utilizing a Ti target modified with 1-6 Ni inserts. The first catalysts series (samples 1-5) was deposited under the total pressure of 6 × 10−3 mbar (16% water vapor), while for the second series (catalysts 6-9) the total pressure was 3 × 10−3 mbar (33% H2O). XRD data showed that Ni could accommodate to the titania matrix only within certain concentration limits. Ni presence in the catalysts composition does not influence significantly the morphology or the electric properties of the films, but exhibits a strong influence over the photocatalytic properties. The highest conversion in the photocatalytic decomposition of acetone was obtained in the first catalysts series for sample 2 (0.41 Ni at.%, conversion rate 47%), while in the second series, the most active catalyst was sample 7 (0.13 Ni at.%, conversion rate 25%). Reusing sample 3 for several runs leaded to an improvement in its catalytic behavior. The photocatalytic activity was found to be strongly influenced by the amount of Ni and the deposition conditions.