Construction Of ZnO Heterostructure And The Photocatalytic Properties

With the improvement of living standards,environmental pollution and energy crisis have become an urgent problem.For advanced oxidation processes as semiconductor photocatalyst surfaces,visible light-driven photocatalysis can be used to decompose organic pollutants into CO₂ by solar energy conversion.And other small molecular substances to cope with the increasingly serious environmental pollution.Among the many photocatalysts currently,zinc oxide?ZnO?has been widely used in the photocatalysis industry due to its special electronic structure,various morphologies,easy manufacture,low cost,and even for the micro electric field caused by the piezoelectric effect.However,the 3.2 eV ZnO with a large band gap can only absorb about 4%of the ultraviolet light in the entire solar spectrum,and even the electrons and holes excited by the ultraviolet light can easily recombine with each other,and the photocatalysis is severely suppressed.performance.Particularly for visible light photocatalysis,it is therefore necessary to modify the ZnO semiconductor by expanding the range of light absorption to successfully excite electron-hole pairs.In this paper,a flower-like zinc oxide nanorod was synthesized by hydrothermal method.AgI/ZnO,Ag₃VO₄/ZnO and AgI/Ag₃VO₄/ZnO nanoheterojunctions were synthesized by one-step chemical deposition.Three heterojunctions were tested by XRD,SEM,DRS,Uv-vis and other characterizations.The photocatalytic performance and cycle performance of three heterojunctions were investigated.The experimental mechanism was explored by means of simulation calculation.The main research contents of this article are as follows:?1?Using citric acid as an inducer and zinc acetate dihydrate as the main raw material,flower-like ZnO was synthesized by hydrothermal method.Ag₃VO₄/ZnO binary heterojunction was synthesized by uniformly loading silver vanadate nanoparticles on the surface of ZnO.It has high degradation efficiency for RhB solution and MB solution.It is more efficient than ZnO and Ag₃VO₄ alone.The load attributed to Ag₃VO₄ increases the response range of visible light while improving the separation efficiency of electron-hole pairs.Finally,it was found through capture experiments that electrons and holes are the main active free radicals.?2?The flower-like ZnO was synthesized by the same method,and the AgI nanoparticles were uniformly supported on the surface of the ZnO nanorod.The photocatalytic degradation of TO,RhB and MO target pollutants was carried out,and the effects of the loading ratio of AgI,the amount of catalyst and the initial concentration of dye on the photocatalytic performance were investigated.When the load ratio reaches 10%,the degradation efficiency reaches 96%for RhB.And the rate of degradation of the heterojunction is three times that of AgI alone.High degradation efficiency was maintained after six cycles of experimentation.The band gaps of AgI,ZnO and AgI/ZnO were calculated by the ZnO combination of simulation and experiment,and the electrons and holes played a major role in the photocatalytic degradation process.?3?Based on the binary heterojunction AgI/ZnO and Ag₃VO₄/ZnO,the ternary heterojunction AgI/Ag₃VO₄/ZnO was synthesized by one-step precipitation method.With RhB and MB as the target degradants,under the irradiation of visible light,the ternary heterojunction is greatly improved compared with the binary heterojunction while maintaining high degradation efficiency.When the loading ratio of iodide ion to vanadate ion reaches 10%and 15%,the highest photocatalytic degradation efficiency is achieved.It was also found by capture experiments that electrons and holes are the main active free radicals during photocatalytic degradation.