Study On The Design Of Multicomponent Micronano Composite And Photocatalytic Properties Of ?-Fe₂O₃/Cu₂O

The current rapid industrial development causes worldwide environmental pollution and energy shortage issues.Photocatalysis is an effective technology that can convert solar energy into clean energy,solve organic pollutants.However,photocatalysts exist the disadvantages of low utilization of sunlight energy and low charge-separation efficiency.What's more,some semiconductor materials have poor photochemical stability and are prone to photocorrosion.Nowadays,the modification of traditional semiconductor materials mainly includes adjusting the morphology,metal or nonmetal ions doping,loading with cocatalysts,constructing heterojunctions and dye-sensitized,etc.Haematite and cuprous oxide are a promising semiconductor nanomaterial in the photocatalysis field,with low cost high natural abundance and low toxicity.However,they have many problems such as low light absorption coefficient,poor conductivity,short carrier lifetime,and slow photocatalytic reaction activity.This research work based on the above background is mainly divided into the following parts:(1)Using ion doping,loading the cocatalyst and constructing heterojunctions,explore the influence of each component on the utilization of light,the photocurrent density of the photoanode.The F-FeOOH nanorods was prepared and synthesized on conductive glass(FTO)by hydrothermal and doping method;and finally,the F-doped Fe₂O₃ nanorods were synthesized by annealing at high temperature.Next,Au and Cu₂O were loading on the surface of Fe₂O₃ by photoreduction and electro-deposition method respectively to form F-Fe₂O₃/Au composite,F-Fe₂O₃/Cu₂O and F-Fe₂O₃/Au/Cu₂O composite.F-doped Fe₂O₃and binary composite catalysts F-Fe₂O₃/Au exhibit greatly enhanced the photocurrent compaired with Fe₂O₃.This is because the doping of F into the lattice of Fe₂O₃,which prevents the recombination of photogenerated electron-hole.The excited electrons in the Au nanoparticle are injected into Fe₂O₃ semiconductor increasing photocatalytic activity.However,the photocurrent of F-Fe₂O₃/Au/Cu₂O composite is bed when loading Cu₂O.Through photoelectrochemical characterization,F-Fe₂O₃/Au/Cu₂O composite can charge under photoelectrochemical process and discharge without bias voltage.The XRD patterns of F-Fe₂O₃/Au/Cu₂O samples after discharge shows the Cu O diffraction peaks.According to the above,we proposed the photo-/electro-catalysis reaction mechanism.(2)On the basis of the first part research,in order to understand the possibilities that Fe₂O₃ semiconductor can be used as photocatalytic degradation materials,this study selected hollow Fe₂O₃/Au/Cu₂O composites to degradation tetracycline(TC).Hollow spheres-like Fe₂O₃ was prepared by simple hydrothermal method,and Fe₂O₃ was annealed at high temperature.Following,the Fe₂O₃/Au,Fe₂O₃/Cu₂O nanocomposite and hollow core-shell Fe₂O₃/Au/Cu₂O ternary nanocomposite were engineered by photoreduction and hydrothermal method.In Fe₂O₃/Au system,the Au nanoparticles with large work function may collect the photogenerated electrons from the conduction band of Fe₂O₃,which can inhibit the recombination of photogenerated carriers.The p-n junction formed by introducing of p-type semiconductor Cu₂O on Fe₂O₃ surface can greatly improve the charge separation efficiency of photocatalyst.The Fe₂O₃/Au/Cu₂O system shows higher photocatalytic activity compared with the Fe₂O₃/Au and Fe₂O₃/Cu₂O systems.The active species trapping experiments illustrate that the reactive species that play a key role in photocatalytic degradation are holes and superoxide radicals.According to the above,the transferred pathway of electrons is presumed to be novel Z-scheme heterojunction,which can improve photocatalytic activity.(3)In order to enhancing the photostability of Cu₂O,Cu₂O@FeOOH yolk-shell nanostructures are successfully synthesized via template-engaged redox etching engineering to perform yolk-shell structures for protecting Cu₂O from photocorrosion by us.Firstly,monodispersed Cu₂O nanocube with size-uniformed were synthesized by using the chemistry reaction,then Cu₂O@FeOOH yolk-shell nanostructures were synthesized at different times by redox etching.FeOOH was used as a conducting channels to transport excited holes from Cu₂O to the surface,suppressing the photocorrosion.Additionally,the photodegradation efficiency and stability of the optimal Cu₂O@FeOOH composites toward tetracycline(TC)enhanced compared with pure Cu₂O nanoparticles.