| Bismuth oxyiodide(BiOI)semiconductor materials have attracted extensive attention due to their special layered structure,suitable band gap,strong light absorption,photochemical stability and flexible tunability.Its research in the fields of photocatalytic degradation and hydrogen production is becoming a hot spot.However,BiOI monomer materials have many common problems of semiconductor materials:the rapid recombination of photo-induced charge pairs will greatly limit their practical applications.Therefore,in order to enhance the photocatalytic activity of BiOI,nanocomposites that reduce the rapid recombination of photogenerated electron-hole pairs and effectively improve carrier separation are prepared.In this study,Ag2MoO4 was selected as a co-catalyst supported on BiOI nanosheets,and a ternary semiconductor photocatalytic material of BiOI,BiOCl and Co was prepared by onestep hydrothermal method,and the photocatalytic degradation mechanism of Rhodamine B by semiconductor composites was explored.The main research contents are as follows:(1)The BiOI semiconductor material is prepared by a simple hydrothermal method.For the first time by growing Ag2MoO4 nanoparticles on the BiOI nanosheets prepared by the hydrothermal method,the p-n scheme heterojunction constructed by Ag2MoO4/BiOI nanomaterials can effectively improve the separation and transport efficiency of photogenerated electron-hole pairs,and improve the photocatalytic degradation activity.The results of photocatalytic degradation experiments showed that after 40 min of visible light irradiation,the composite photocatalyst with Ag2MoO4/BiOI ratio of 60%had a degradation rate of 99.4%for Rhodamine B,which was 3.17 times and 7.55 times that of Ag2MoO4 and BiOI monomers,respectively.Through the combination of XPS,SEM,XRD,UV-vis DRS and electrochemical test results,it is proved that after illumination,photoexcited carriers transfer photogenerated electron-hole pairs through the constructed p-n scheme heterojunction at the interface,which accelerates the The separation and transport efficiency of photogenerated electron and hole pairs inhibits the recombination of carriers,thereby effectively improving the photocatalytic efficiency.(2)Co/BiOCl/BiOI ternary semiconductor composites were prepared by a onestep hydrothermal method for the first time.Photocatalytic degradation of target RhB by irradiation of xenon lamp.The photocatalytic efficiency of 35wt%Co/BiOCl/BiOI nanocomposites was relatively higher than that of pure BiOI and BiOCl.The target RhB tends to be completely degraded in 60 minutes,and the degradation rate reaches 99.07%.The free radical trapping experiment confirmed the role of superoxide radicals and holes in the photocatalytic degradation of RhB.On this basis,a possible mechanism of RhB degradation under visible light irradiation is proposed:the composite photocatalyst with S-scheme heterojunction has a strong internal electric field,and its strong driving force effectively solves the problem of photogenerated electron-hole pair separation and The problem of low migration efficiency,the construction of the heterojunction promotes the effective separation of photogenerated charge pairs is the main reason for the enhanced photocatalytic performance,and at the same time,due to its good energy potential matching,it has a good synergistic effect,which increases the absorption of visible light and prolongs the time.The lifetime decays and the interfacial charge transfer between Co/BiOCl/BiOI is improved. |
