Preparation And Photocatalytic Properties Of Bi₂MoO₆ Modified Micro-nano Composites

Semiconductor photocatalysis technology has been widely researched in the field of environmental treatment because of its advantages such as low cost and high efficiency.An ideal photocatalyst should have the advantages of narrow band gap energy,good stability and high visible light absorption and conversion efficiency.Recent studies have shown that Bi₂MoO₆ has a narrow band gap（2.5-2.8 e V）and has a significant photoresponse to visible light,thus exhibiting excellent visible photocatalytic activity.In this paper,a variety of heterostructures,including Bi₂MoO₆/ZnO,Bi₂MoO₆/C and Bi₂MoO₆/C/ZnO,were obtained with Bi₂MoO₆ as the main body,and the three composites were investigated using various characterization tools,and the main research contents and results are as follows:Bi₂MoO₆/ZnO heterojunction photocatalysts were firstly prepared by the solvothermal method.The optimal reaction conditions（180℃,12 h）for Bi₂MoO₆ were determined by analyzing the photocatalytic results of Bi₂MoO₆ samples obtained at different hydrothermal times under visible light.The flower-like hollow sphere structure of Bi₂MoO₆ was subsequently used as the growth substrate for loading ZnO nanoparticles.The heterogeneous structure broadened the response of ZnO to visible light,and the migration of holes from the valence band of ZnO to BMO formed an effective internal electric field,which further accelerated the separation of electron-hole pairs and reduced the probability of carrier complexation near the Bi₂MoO₆/ZnO heterojunction.The best composite mass ratio of Bi₂MoO₆/ZnO（w%=40）achieved 92.1%degradation of methylene blue（MB）dye under simulated visible light conditions.Subsequently,inorganic C with narrow band gap but low photocatalytic efficiency was selected as the modified material,and the C spheres were more uniformly dispersed by morphological modulation of C to form the Bi₂MoO₆/C structure.The degradation rates of the composite Bi₂MoO₆/C heterostructured photocatalysts obtained at different reaction times were explored for MB,and the maximum degradation rate was determined to be 93.3%under the optimal reaction conditions（180℃,12 h）.The improvement of the photocatalytic activity of the composites was mainly from the increase of the photogenerated charge carrier separation efficiency and the increase of visible light absorption.The carbon layer acted as an electron reservoir in the composite,and the photoexcited electrons were transferred through the interface between Bi₂MoO₆ and the carbon layer.Finally,the in situ solvent thermal composite of ZnO on spherical Bi₂MoO₆/C was carried out to explore the degradation rate of MB by the Bi₂MoO₆/C/ZnO heterostructured composite photocatalyst obtained under different reaction conditions,and it was determined that the maximum degradation rate of MB dye by the ternary composite under the optimal reaction conditions（180℃,6 h）was 85.1%under simulated visible light conditions.The ZnO nanoparticles particles were uniformly dispersed on the Bi₂MoO₆/C surface,the specific surface area of the composite increased,the pore size increased,the hollow porous channel structure and the increased specific surface area enhanced the number of reflections,and the multiple reflections enhanced the absorbance,thus improving the photocatalytic performance.In this dissertation,the preparation of Bi₂MoO₆ with other semiconductor photocatalysts under different conditions and its photocatalytic performance for dye degradation are investigated,and its photocatalytic mechanism is also described.The above content provides some research ideas for the development of new photocatalytic materials.