Fabrication and characterization of TiO2 photocatalytic thin film prepared from peroxo titanic acid sol

A novel sol-gel technique using the PTA (peroxo titanic acid) sol as precursor for the fabrication of TiO2 photocatalytic thin film is introduced in this paper. The peroxo titanic acid sol was synthesized from titanyl sulfate (TiOSO4), ammonia and peroxide solution (H2O2). The transparent and porous TiO2 thin film was prepared via a sol-gel technique using PTA sol and polyethylene glycol (PEG) as precursor and template, respectively. The TiO2 thin film samples were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectrophotometry (UV-vis), X-ray photoelectron spectrum (XPS) and thermogravimetry and differential thermal analysis (TG-DTA) technique. The PTA sol displayed amorphous TiO2 below 100 degrees C. The anatase phase formed at 200 degrees C to 700 degrees C. The crystallinity of anatase phase was improved with increasing temperature. The anatase crystals on the surface of TiO2 film were strip-like, the size being about 100 nm in length and 40 nm in diameter. Addition of PEG to the PTA sol developed porous structures in the film and changed the size and shape of the particles. The surface of the film contained Ti, O and C elements and Na element that diffused into the film from the glass substrate. The photocatalytic performance of TiO2 film was tested for the degradation of 10 mg/L methyl orange. The degradation of methyl orange solution reached 98.9% after irradiated for 180 min under UV light. The porous TiO2 thin film exhibited high photocatalytic activity towards degrading methyl orange.