Hierarchical Nanoflower-Ring Structure Bi2O3/(BiO)2CO3 Composite for Photocatalytic Degradation of Rhodamine B

Hierarchical nanoflower-ring structure Bi2O3/(BiO)(2)CO3 (BO/BCO) composite was successfully synthesized by the temperature-programmed hydrothermal treatment. X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (UV-Vis/DRS), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and N-2 adsorption-desorption tests were employed to characterize the crystalline phase, chemical composition, optical absorption properties, morphology and surface physicochemical properties of as-synthetized material. The results showed that the crystalline phase of (BiO)(2)CO3 was tetragonal phase, and the crystalline phase of Bi2O3 was the monoclinic phase in as-composite Bi2O3/(BiO)(2)CO3 which had both as -crystal structures. Moreover, with the introduction of OH and reaction time increasing in synthesis process, the intensity of characteristics diffraction peak of (BiO)(2)CO3 was gradually decreased, meanwhile, that of Bi2O3 was gradually increased, showing that the proportions of Bi2O3 were increased in the sample with reaction time increased. The results of UV-Vis/DRS analysis showed that the absorption edge of as-synthetized composite BO/BCO had shift compared to pure Bi2O3 and pure (BiO)(2)CO3, and the absorption was effectively increased in the visible light region with the introduction of Bi2O3. At the same time, (BiO)(2)CO3 nanolayer was changed to the hierarchical nanoflower-ring structure BO/BCO-0.5 composite, and the formation of special morphology leads to narrowed band gap and change the reflection and scattering of photoelectrons, which were conducive to the absorption efficiency of light and transfering of photogenerated charges. In addition, the photocatalytic activities of as-composites BO/BCO were studied by degradation photocatalytic experiments of RhB as the model molecule under different light irradiation, the cycle experiment and the capture experiment. The results of photocatalytic activity experiment showed that the activity of BO/BCO-0.5 was significantly higher than that of other systems (Bi2O3 and P25), and the photocatalytic activity of BO/BCO-0.5 was kept even after three cycles. Meanwhile, according to the capture experimental results, the possible photocatalytic reaction mechanism of BO/BCO composite was speculated.