Preparation And Photocatalytic Properties Of BiVO 4 And Its Composites Controlled By Crystal Phase And Morphology

Recently, with the increasing of more serious polluted problems in environment, photocatalystic organic pollutants degradation of semiconductor catalysts have received numerous attentions. While the synthesis of photocatalytic semiconductor have played a key role in environmental remediation. The morphology and crystal structure of photocatalysts have considerable influence on the photocatalystic activities. Therefore, it is necessary to prepare the semiconductor photocatalysts with suitable morphology and crystal structure. In this paper, BiV04 photocatalysts with different morphology and crystal structure were synthesized via a facile low-temperature coprecipitation method under controlling the reaction condition. While BiVO4 microspheres with controllable crystalline phases were synthesized by coupling a simple low-temperature coprecipitation method with annealing treatment. m-BiVO4@CeO2 hollow microspheres have been also fabricated by a facile low-temperature co-precipitation method and subsequent annealing process. The obtained photocatalysts were characterized by powder X-ray diffraction (XRD), scanning electron microscopy(SEM), UV-vis absorption spectra, Diffuse reflectance spectra (DRS), Raman spectra and X-ray photoelectron spectroscopy (XPS). The photocatalytic properties of these photocatalysts were further investigated by evaluating on photodegradation of the model pollutant rhodamine B (RhB) under both the UV light and visible light. The mechanisms of enhanced activity in photodegradation pollutants were also explored.(1)BiVO4 microspheres with controllable crystalline phases, including tetragonal, tetragonal-monoclinic heterophase and monoclinic, were synthesized by coupling a simple low-temperature coprecipitation method with annealing treatment. The results indicated that the monoclinic BiVO4 microspheres were achieved by high temperature annealing treatment of the as-obtained tetragonal BiVO4 microspheres. The morphology and size of the monoclinic BiVO4 microspheres were kept unchanged. The photocatalytic activities of BiVO4 microspheres with different crystalline phases were evaluated by degradation of Rhodamine B (RhB) under both ultraviolet light and visible light irradiation, respectively. The relationship between different crystalline phases and photocatalytic activities was discussed in detail, which would provide an insight into the intrinsic reasons for the diversity in photocatalytic activity of BiVO4 catalysts with different crystalline phases.(2)m-BiVO4@CeO2 hollow microspheres have been fabricated by a facile low-temperature co-precipitation method and subsequent annealing process. The visible-light-driven photocatalystic performances were evaluated by degradation for RhB dye molecules, demonstrating that the as-fabricated m-BiVO4@CeO2 hollow microspheres exhibit the enhanced photocatalystic activity, compared to the obtained pure m-BiVO4 microspheres. The separation of photoinduced electron-hole pairs and transfer between CeO2 and BiVO4 has been discussed in detail, in order to have in-depth understanding on the enhanced photocatalytic performance. The results indicate that the enhanced photocatalystic activity of the as-fabricated m-BiVO4@CeO2 hollow microspheres is attributed to the efficient separation of the photoexcited electrons and holes.