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

Abstract

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 °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 high-resolution 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 ~100 nm and ~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 > λ > 400 nm). Therefore, small monodisperse CeO₂/Bi₂O₃ nanospheres were designed by a simple route with efficient photocatalytic activity.