Study On The Photocatalytic And Mechanical Control Properties Of Ferroelectric/3D Graphene Composites

In recent years,various provinces and cities had a large-scale haze in our country.Environmental pollution problem is a serious threat to people's health and production and living environment.The emergence of photocatalytic technology makes the problem to be solved.At present,the visible light utilization efficiency of photocatalyst materials is not high.Bismuth ferrite becomes a hot material because of its unique spontaneous polarization and narrow band gap can effectively separate the photogenerated carriers and extend the range of photocatalytic light response to the visible region.Three dimensional grapheme becomes a hot materials in semiconductor composites because of its large surface area can enhance the catalytic activity,and its good electron transfer ability can be used as carrier matrial.In this paper,we prepared bismuth ferrite?BiFeO₃?/three-dimensional graphene composite materials by hydrothermal method,the experimental analysis is also carried out.It is expected that synergy of the two advantages to improve the photocatalytic activity and use piezoelectric effect of ferroelectric materials to realize the mechanical-photocatalysis under mechanical control.The specific research works are as follows:?1?Graphene oxide was prepared by Hummers method,three-dimensional graphene and BiFeO₃ submicron cube,BiFeO₃ nanospindles,BiFeO₃ submicron Hydrangea,BiFeO₃ nanorods,BiFeO₃ submicron cube/3D graphene composites,BiFeO₃ nanospindles3D/graphene composites,Bi FeO₃ submicron hydrangea/3D graphene composites were synthesized by hydrothermal method.?2?This part mainly studied the degradation effect of MB of BiFeO₃ crystals with threedifferent morphologies including BiFeO₃ submicron cube,BiFeO₃ nanospindles,BiFe O₃ submicron Hydrangea,under different action condition of visible light and H2O2,and the first order kinetic curve was fitted.The reasons for different catalytic properties of three morphologies of BiFeO₃ crystals with different conditions were compared and analyzed.It was found that a new class of Fenton-like reagent was formed when BiFeO₃ and H2O2 work together by adding H2O2,and then,they combine with light to produce the optical fenton effect under visible light irradiation,which significantly enhanced catalytic activity.In comparison,the catalytic ability of BiFeO₃ submicron hydrangea with special morphology than the other two morphology's of BiFeO₃ crystal.?3?This part mainly studied the crystallization process of BiFeO₃ submicron cube and the visible light photocatalytic properties of bismuth ferrite/three-dimensional graphene composites with different morphologies.Firstly,the effects of hydrothermal time and precursor pH value on the formation of pure phase of BiFeO₃ were investigated,and the morphology optimization of BiFeO₃ submicron cube with precursor pH value was also analyzed;Secondly,a three-dimensional porous structure graphene with excellent mechanical properties was prepared by a simple method;Furthermore,the effects of the concentration of graphene oxide on the photocatalytic properties of BiFeO₃ submicron cube/three-dimensional graphene composites were studied deeply,then the best proportion of the composite material was obtained;Finally,the photocatalytic performance of BiFeO₃ submicron spindle/three-dimensional graphene composites and Bi FeO₃ submicron hydrangea/three-dimensional graphene composites under the optimum proportion were studied.?4?An ultrasonic catalytic device was designed to realize the effective mechanical force applied to the catalyst.Mechanical catalysis induced by piezoelectric effect in ferroelectric materials and mechanical photocatalytic properties with the combination of mechanical catalysis and photocatalysis were studied.The study was carried out from single material to composite material: Bi FeO₃ submicron cube,BiFeO₃ nanorods,and BiFeO₃ submicron cube/three-dimensional graphene composites under the optimum proportion.The results show that the composite system has excellent photocatalytic activity.In summary,a new type of bismuth ferrite/three-dimensional graphene composites were prepared in this paper,and the photocatalytic performance of the two under the optimumproportion were annalysed deeply,the results show that the composite system has excellent photocatalytic activity.On this basis,an ultrasonic catalytic device was designed to realize the effective mechanical force applied to the catalyst.Mechanical catalysis induced by piezoelectric effect in ferroelectric materials and mechanical photocatalytic properties with the combination of mechanical catalysis and photocatalysis were studied.The results show that the composite system has excellent mechanical photocatalytic activity.