Photocatalytic activity of Al₂O₃ improved by the addition of Ce³⁺/Ce⁴⁺ synthesized by the sol-gel method. Photodegradation of phenolic compounds using UV light

The materials Al₂O₃:Ce³⁺/Ce⁴⁺ (cerium content 0.5, 1.0, 3.0, and 5.0 wt.%) were synthesized by the sol-gel method. The materials were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), N₂ physisorption, UV–Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX); also, some electrochemical tests were performed for the materials characterization. The materials were evaluated in the phenol photodegradation using UV light. The photocatalyst containing 1.0 wt.% cerium (AC1.0) presented the highest photoactivity than the others synthesized samples. This catalyst was selected to photodegrade others phenolic derivatives such as 4-chlorophenol, p-cresol, and 4-nitrophenol. All the synthesized photocatalysts by the sol-gel method showed a better activity than (TiO₂, P25 Degussa). The photodegradation reactions were followed by UV–Vis spectroscopy and total organic carbon TOC. A reaction mechanism is proposed involving the sensitization of the organic molecule on Al₂O₃:Ce³⁺/Ce⁴⁺ with UV light for its mineralization.