TiO2 nanowires on Ti thin film for water purification

We report about the synthesis of rutile TiO2 nanowires (NWs) by thermal oxidation (700 °C for 4 h in a mixed flow of argon and oxygen) of a sputtered titanium thin film (325 nm) on glass substrate covered by a thin layer of gold as catalyzer. We studied the morphological and structural characteristics of the sample by scanning electron microscopy and Rutherford backscattering analyses. NWs are uniformly distributed on the surface with size up to 500  nm in length and up to 100 nm in diameter. We investigated the photocatalytic activity and the photonic efficiency in the degradation of the Methilene Blue (MB) dye. In order to remark the contribution of the NWs in the process, we compared the photocatalytic activity with the one of the annealed TiO2 thin film substrate without NWs. The photocatalytic rate per unit area for the sample with and without NWs resulted to be (2.52±0.06)·10−3 cm−2 min−1 and (1.26±0.02)·10−3  cm−2 min−1, respectively; the photonic efficiency (in %) of the MB degradation was estimated as 0.021±0.006 and 0.021±0.006, respectively. These results suggest an improvement of the photocatalytic properties due to the presence of the TiO2 NWs on the film.