Biotemplated synthesis of 3D rare earth-doped TiO2 hollow spheres for photocatalytic application

Three-dimensional (3D) titania (TiO2) hollow spheres doped with rare earth elements were successfully synthesized via a nonhydrolytic sol-gel method using lotus pollen as a biotemplate and a cationic surfactant as a co-template. The as-prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption-desorption isotherms, photodegradation tests, and UV-vis diffuse reflectance spectroscopy. The results indicate that the 3D TiO2 hollow spheres have a structure similar to that of lotus pollen. The Brunauer-Emmett-Teller specific surface areas of 3D TiO2 and 3D Gd-La-co-doped TiO2 are 94.90 and 88.62 m(2) g(-1), respectively, which are higher than for a commercial TiO2 sample (P25). In addition, 3D TiO2 in combination with rare earth element co-doping can extend light absorption to the visible region and enhance photocatalytic activity for the degradation of methyl orange under simulated solar irradiation as compared with P25 and pristine 3D TiO2. The superior photocatalytic activity is mainly attributed to the higher specific surface areas and the doping with rare earth elements.