CeO2/Co3O4 hollow microsphere: Pollen-biotemplated preparation and application in photo-catalytic degradation

Lotus pollen was used as biotemplate to produce the CeO2/Co3O4 hollow microsphere for photo-catalytic degradation of methylene blue (MB) and tetracycline (TC). The synthesized materials were systematically characterized by X-ray diffraction (XRD), scanning election microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron (XPS), N-2 physisorption, Fourier transform infrared spectroscopy (FT-IR) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The results showed that the catalysts can perfectly duplicate the morphology of the pollen, and CeO2/Co3O4 composite exhibited the typical hollow-microsphere structure with the external diameter of about 26 mu m and a high specific surface area of 48.1 m(2) g(-1). Compared with the CeO2 hollow microsphere prepared by the same method, the photocatalytic degradation performance of the CeO2/Co3O4 hollow microsphere was much higher due to the enhanced electron transfer deriving from the synergistic effect between Co and Ce species. The degradation rate of MB under xenon lamp was above 95% within 90 min, and the degradation rate of TC was above 90% within 60 min. In addition, CeO2/Co3O4 hollow microsphere showed high reusability, which could be reused for four cycles without significant decrease of activity for the degradation of both MB and TC.