Synthesis of monodisperse Bi2O3-modified CeO2 nanospheres with excellent photocatalytic activity under visible light

In this work, monodisperse CeO2/Bi2O3 nanospheres were successfully synthesized via the three-step method, which is a traditional hydrothermal dip-coating-anneal method, and subsequent facile calcination at 600 degrees C for 4 h. The structure of obtained products was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and highresolution transmission electron microscopy (HRTEM). The results showed that highly uniform CeO2 microspheres and monodisperse CeO2/Bi2O3 nanospheres were obtained, the sizes of CeO2 microspheres and CeO2/Bi2O3 nanospheres were similar to 100 nm and similar to 125 nm. Besides that, the photocatalytic activities of CeO2/Bi2O3 nanocomposites were evaluated by photodegradation of Rhodamine B (RhB) under visible light. CeO2/Bi2O3 nanospheres exhibited a wide visible-light absorption with an edge at ca. 800 nm, which indicated a wide red shift compared to that of individual CeO2 microspheres (ca. 450 nm) and individual Bi2O3 nanoparticles (ca. 450 nm). Furthermore, the obtained CeO2/Bi2O3 nanospheres had remarkable photocatalytic degradation activities of dye under visible light compared with the activities of two individual photocatalysts of CeO2 microspheres and Bi2O3 NPs with the same concentration. The higher photocatalytic degradation activities of the photocatalysts could be ascribed to the following factors: (1) a large specific surface area of CeO2/Bi2O3 nanospheres with small size, (2) the efficient separation of photogenerated electrons and holes of the photocatalysts, and (3) a wide visible-light photoabsorption range (700 nm > lambda > 400 nm). Therefore, small monodisperse CeO2/Bi2O3 nanospheres were designed by a simple route with efficient photocatalytic activity.