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Pure titanium dioxide (TiO 2 ) and nitrogen (N)-doped TiO 2 nanorods array were prepared using polished Ti substrates and hydrothermal synthesis method. Prepared nanorods films were characterized by different techniques including X-ray diffractometer (XRD), field-emission scanning electron microscope, Fourier-transform infrared spectroscopy, and XPS. The photocatalytic activities of both prepared films were evaluated by their capacity to degrade methylene blue (MB) in solution, and an attempt to associate it with their surface wetting properties is achieved. The XRD results showed that the prepared TiO 2 is of rutile phase. Furthermore, the 3%N-doped TiO 2 nanorods films show similar high crystallinity and photocatalytic activity compared with prepared films of TiO 2 rutile phase. Additionally, their surface wetting properties were studied and showed hydrophobic behavior with contact angle higher than 120°. The hydrophobicity of 3%N-doped TiO 2 nanorod films is shown to be enhanced because of TiO 2 nanorods diameter decreasing. Additionally, the results clearly show that the prepared 3%N-doped TiO 2 nanorods films exhibit both higher hydrophobicity and the best photocatalytic activity toward the degradation of MB under visible light irradiation.

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TiO2 nanowire‐nanoparticle hetero‐structured films were prepared via a sol–gel method and coated on glass substrates by dipping method for photocatalytic activity. In this study 0, 1, 3, and 5 mol% of Ni doped were studied. One‐dimensional TiO2 nanowires (NWs) were prepared by hydrothermal treatment with TiO2 nanoparticles (NPs) which are commercially available. XRD, FESEM, DRS, and XPS were used to characterize the prepared nanowire‐nanoparticle hetero‐structures films. 3%Ni doped TiO2 hetero‐structured film (TNi3) had the highest photocatalytic activity on the degradation of methylene blue (MB). TNi3 films provided about 4.3 times of degradation rate compared to undoped TiO2 (T). It revealed that TNi3 film resulted in shifting the absorption wavelength towards narrowing the energy band gap and small crystallite size. Therefore, the TNi3 film exhibited a photocatalytic activity on the degradation of MB under visible light irradiation greater than undoped film.

TiO2nanorod arrays (TNRs) films were fabricated on the polished Ti substrates using hydrothermal and then annealed for 2 h in air at 300°-500°C. The films were characterized by XRD and FESEM. The photocatalytic activities to degrade methylene blue (MB) in solution were determined, expecting these activities to correlate with the hydrophobic property. The experiment showed that rutile peaks recrystallized at the annealing temperature, with the crystallinity increase with increasing annealing temperatures. The TNRs films annealed at 500 oC had a comparatively high crystallinity of rutile phase as well as the highest photocatalytic activity of the films prepared. Surface wettability was studied by measuring the contact angle of the liquid interface which showed hydrophobic nature as water contact angles were greater than 120°. The results can be concluded that as-prepared TNRs film was annealed at 500 oC exhibits excellent hydrophobicity for water molecules and the highest photocatalytic activity on the degradation of MB under UV irradiation.