Enhanced photocatalytic activity of Eu2O3/Ta2O5 mixed oxides on degradation of rhodamine B and 4-nitrophenol

Europium oxide/tantalum pentoxide (Eu2O3/Ta2O5) mixed oxides with different Eu2O3 dopings were prepared by a single-step sol–gel process via hydrolysis of tantalum pentachloride in the presence of europium nitrate. The products were in the amorphous and orthorhombic phase structures, respectively, based on the different calcination temperatures (200 and 500 °C). Composition, morphology, phase structure, Eu2O3-doping mode in the Ta2O5 matrix and optical absorption property of the products were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), field emission scanning electron microscopy (FESEM), X-ray diffraction patterns (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (UV–vis/DRS). The UV-light photocatalytic activity of the products was evaluated by degradation of aqueous rhodamine B (RB) and 4-nitrophenol (4-NP). The results showed that the photocatalytic activity of as-prepared Eu2O3/Ta2O5 was higher than that of pure Ta2O5 regardless of their phase structures. Among the tested samples, Eu2O3/Ta2O5 with 0.49% Eu loading obtained with 200 °C exhibited the highest activity to degradation of the above two model molecules. The reasons of this enhanced photocatalytic activity were discussed.