Studies On The Modification And Properties Of Bismuth Molybdate Photocatalyst

Bismuth molybdate,as a new kind of bismuth system material,shows unique advantages in the photocatalytic reaction and has received extensive attention.In this paper,the modification of bismuth molybdate was studied by doping and compound method.The physical and chemical properties of the samples were characterized by X-ray diffraction?XRD?,field emission scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?,Brunauer-Emmett-Teller?BET?surface area,UV-visible diffuse reflectance spectroscopy?UV-vis DRS?,and photoluminescence emission spectra?PL?.And the photocatalytic activity of the as-prepared samples was evaluated towards photodegradation of RhB aqueous solutions.Bi₂MoO₆ nanosheets with the different Lanthanum contents were prepared by the facile hydrothermal method.Results indicated that Bi₂MoO₆ nanosheets selectively exposed?0 0 1?facets as the main external surfaces with the manifold of La content.And the samples of Bi₂MoO₆ with La have shown much smaller crystallites.When the molar ratio of La:Bi is 0.5%,the obtained Bi₂MoO₆ sample exhibited the highest catalytic performance for RhB degradation under the visible light,which can be attributed to the synergic effect of broad light absorption range,the catalystoptimum bandgap and the effectively separation of photogenerated electron-hole.The possible photolytic degradation mechanism was further discussed and the photogenerated holes?h+?was found to be the major active species.Besides,the La₂O₃ formed in the surface can provide a path for electron transfer.The Fe₂O₃/Bi₂MoO₆ samples were prepared by introduce Fe₂O₃ into Bi₂MoO₆,and the composite catalyst has shown higher photocatalytic activity.The experimental results certified that the crystal growth of Bi₂MoO₆ nanosheets can be inhibited and the samples were tend to formed much thinner nanosheets in the presence of Fe₂O₃.More active sites can be exposed in the surface of the ultra-thin nanosheets.The interface formed between Fe₂O₃ and Bi₂MoO₆ heterostructures can promote electron transfer.The high photocatalytic activity can attributed to the synergistic effect of the broad response range of photocatalytic,narrow band gap,high specific surface area and low recombination of photogenerated electrons and holes by composite Fe₂O₃ with Bi₂MoO₆.When the mass fraction of Fe₂O₃ is 1.8%,the sample exhibited the best photocatalytic,and the photogenerated hole is the main active species during the whole photocatalytic process.