Titania and copper-loaded titania were synthesized by an improved sol-gel method using a homogeneous hydrolysis technique. Unlike the conventional sol-gel procedure that added water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Fourier transform infrared spectra confirmed the presence of bidental ligand. The sol was dried, then calcined at 500°C to remove organics and transformed to anatase titania. Transmission electron microscopy revealed that the titania particles were uniform, and the particle size ranged from 10 to 25 nm. The band gaps of TiO2 and Cu/TiO2 ranged from 3.01 to 3.17 eV based on the diffusive reflective ultraviolet-visible spectrometry. X-ray photoelectron spectroscopy analysis showed a positive shift of binding energy of Ti2p3/2 and a negative shift of Cu 2p3/2 in Cu/TiO2. The redistribution of electric charge is due to the Schottky barrier of Cu and TiO2.

The hydrophilic properties of amorphous TiOx films prepared by different methods, e.g., radio frequency (rf) sputtering and plasma-enhanced chemical vapor deposition (PECVD), were studied. It was found that the hydrophilicity strongly depends on the film structure. The best hydrophilicity was realized with the PECVD amorphous film having distorted Ti–O bonds due to a large amount of OH groups. These characteristics of the PECVD amorphous film suggest that such a low-density film including distorted Ti–O bonds could increase the photoenhancement efficiency by ultraviolet radiation. This reason is also supported from the results that a low-density rf sputtered film presented a higher hydrophilicity compared to a high-density radio frequency sputtered film. Furthermore, both electrical and chemical effects of OH groups will also contribute to the good hydrophilicity of the PECVD film.