Preparation of solar/visible-light active TiO2 photocatalysts with carboxylic acids for the degradation of phenol

TiO2 catalysts were synthesized via simple sol-gel method using different carboxylic acids. The synthesized materials were characterized by UV-Vis spectroscopy (DRS), X-ray diffraction (XRD), N-2 physisorption and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the samples was evaluated in the degradation of phenol under visible and solar light. The prepared catalysts using the carboxylic acids showed an improvement in the characteristics of TiO2. Particularly, the catalyst prepared with citric acid, showed a single pure anatase phase with a small crystallite size (of around 9.4 nm), larger surface area (81 m(2)/g) and narrower band gap (2.94 eV) compared to the non-modified TiO2 and the reference Degussa P25. Moreover, the results showed that using citric acid, a high conversion of phenol under visible light of around 46% was achieved and a complete degradation under sunlight in a shorter time of around 90 min.