Facile Synthesis Of Bi₂MoO₆ /ZnSnO₃ Heterojunction With Enhanced Visible Light Photocatalytic Degradation Of Methylene Blue

As one of the advanced oxidation technologies,semiconductor photocatalysis technology aroused the domestic and international research scholar's widespread interest due to its advantages including high efficiency,environmental protection and energy saving,low cost,which raised a research hot wave of semiconductor photocatalysis technology.However,with the deepening of the research,it was found that the traditional semiconductor has narrow excitation wavelength,the optical excitation generated carrier recombination rate higher,reduces the light catalyst for light energy utilization,seriously limits the development of semiconductor photocatalysis technology.In order to break the current bottleneck and develop a new type of photocatalyst,it is becoming a hot research topic to construct heterogeneous junction by combining with other narrow band gap semiconductor.At present,a series of bismuth semiconductor photocatalyst has been favored by people because of its some advantages including special crystal structure,non-toxic,abundant raw material and so on.Hrein,based on the new semiconductor material molybdate molybdate,the heterojunction was constructed by combining with zinc stannate.Based on this,the specific work of this study is as follows:On one hand,a series of Bi₂MoO₆/ZnSnO₃ photocatalysis composite were successfully prepared by coupling solvothermal with annealing steps.Here,to assess the photocatalytic activity of synthetic compounds,methylene blue was studied as the goal pollutant.The results were showed that the photocatalytic degradation ability of Bi₂MoO₆/ZnSnO₃ was obviously higher than that of the single Bi₂MoO₆,ZnSnO₃.Among them,5-Bi₂MoO₆/ZnSnO₃ displayed the highest photocatalytic activity,and the removal efficiency of methylene blue was up to 95%within 1 h.At the same time,with the help of first-order kinetic model,the photocatalytic oxidation process was also investigated deeply.The highest k value is 0.0508 min^-1 obtained by 5-Bi₂MoO₆/ZnSnO₃,which is up to 24.19 times and 2.29 times compared with ZnSnO₃and Bi₂MoO₆,respectively.In addition,the formation of superoxide free radicals in the process of photocatalytic degradation of methylene blue was also determined by the capture experiment.On the other hand,a series of characterization methods such as TEM,SEM,XRD,XPS,BET,PL,UV-DRS were applied to further reveal the photocatalytic mechanism of Bi₂MoO₆/ZnSnO₃ complex.The analysis results showed that there are a lot of micropores in the zinc sulfonate materials obtained after calcining,and in the composite Bi₂MoO₆ particles were covering on the surface of the cubic phase ZnSnO₃with well dispersity,which improved the surface properties of Bi₂MoO₆/ZnSnO₃complexes.What's more,compared with the single Bi₂MoO₆,ZnSnO₃,the absorption edges of Bi₂MoO₆/ZnSnO₃ hybrids presented gradual red shift with different degree.At the same time,5-Bi₂MoO₆/ZnSnO₃ obtained the highest compound fluorescence intensity,which meaned that the synthesis of composite photocatalytic inhibits the recombination of electrons and holes.In a word,the prepared composite photocatalysis enhanced the absorption capacity of visible light,and also slowed down the recombination rate of electrons and holes.Finally,On the basis of the band theory,the valence band and conduction band potential of Bi₂MoO₆,ZnSnO₃ were calculated,respectively.And,combining a series of characterization analysis results with the experiment of free radicals captured,A sonable photocatalytic degradation pathway was put forward.