The Prepration, Modificaion And Photocatalytic Performance Of Bi₂MoO₆ Photocatalyst

Over the past few years, TiO2 has been widely used and investigated for the photodegradation of organic pollutants in water owing to its cheapness, strong oxidizing power and nontoxicity. However, due to its large band gap（3.2 eV for anataseTiO2）, pure TiO2 can only absorb a small fraction of solar energy. Therefore, in order to effectively utilize solar energy in photocatalytic processes, some visible-light-driven photocatalysts have received great interest. Bi₂MoO₆ is an important Aurivillius oxide, and it is showed that Bi₂MoO₆ also possesses excellent visible-light-driven photocatalytic activity for water splitting and degradation of organic contaminants. But, there is still more than 55 % of solar energy cannot be absorbed by Bi₂MoO₆. In order to further meet the requirement of environmental pollutants treatment, a great deal of effort has been made to develop Bi₂MoO₆ photocatalysts.In this work, the self-assembly process of bismuth molybdate were systematically investigated, and, using bare Bi₂MoO₆ as counterpart, through rare earth ions doping and graphene modification, the photocatalytic performance of hybrid photocatalyst were further enhanced. This study mainly include three aspects which were presented in the following.The flower-like Bi₂MoO₆ hollow spheres were prepared via a solvothermal process in the presence of ethylene glycol. It is showed that the solvothermal time,the addition of the ethylene glycol and a process of calcination had effects on the Bi₂MoO₆ structure and morphology. The best photocatalytic performance were observed when Bi₂MoO₆ was maintained after calcination at 400 ℃ for 3 h.Er-Bi₂MoO₆ microspheres andEr-Bi₂MoO₆ filmswere synthesized by a hydrothermal method using amorphous complex as precursor. As a result, theEr-Bi₂MoO₆ hybrid exhibited excellent photocatalytic activity, which was much higher than that of bare Bi₂MoO₆. The photocatalytic activity enhancement of Bi₂MoO₆ can be attributed to the dopant Er3+, which can transform visible light into ultraviolet light, leading to the broad spectrum photocatalytic activity of as-prepared material. Moreover, the optimal doping level of Er3+was investigated in detail. On the basis of experimental, we can clearly obtain that when the Er3+ concentrations were about 1.0 mol%, the as-prepared samples possess the best photocatalytic performance.Graphene-Bi₂MoO₆（G-Bi₂MoO₆） hybrid photocatalyst were prepared via a simple, one-step method. Specifically, through hydrothermal process, the graphene oxide, which were synthesized by modified Hummers’ method could be successfully incorporated into Bi₂MoO₆ framework and in-situ reduced. According toanalysis, it can be found that, in a certain range, the additional amount of graphene oxide has effects on the relative content of Bi₂MoO₆, structure and morphology of the composite. Additionally, the photocatalytic performance of as-prepared samples were systematicevaluate by the photo-degradation of RhB under simulated sunlight irradiation. By contrast, we can obtain that the as-prepared G-Bi₂MoO₆ hybrid exhibited excellent photocatalytic activity and stability, and, the optimal loading amount of GO（1wt%） can be further confirmed.