The Preparation And Photocatalytic Activity Research For Cu₂ZnSnS₄@TiO₂p-n Heterostructure Nanosheet Arrays

TiO₂ nanomaterials have become a promising nanocrystalline semiconductor material due to its high photocatalytic activity,stability and non-toxicity.It has presented extraordinary application prospects in the field of photocatalytic degradation of pollutants,solar cells.However,the disadvantage of TiO₂ is that its own bandgap is wide and can only absorb the ultraviolet light in the sun and its light quantum efficiency is relatively low,which greatly limits its application in real life.In view of this,it is an effective way to modify the Ti O₂ nanometer material to reduce its own bandgap,broaden its light absorption range and improve the quantum efficiency.The researchers modified TiO₂ nanomaterials by the doping,semiconductor composite and the surface deposition of precious metals.In this paper,based on the research status of photocatalytic degradation of organic pollutants and the influence of catalytic activity on the basis of photocatalytic degradation of TiO₂ nanomaterials,this paper summarizes the preparation of Cu₂ZnSn S₄@TiO₂ p-n heterostructures nanosheet arrays and its photocatalytic performance research.It mainly summarizes the research contents and achievements of the following two aspects:1.Firstly,the orientated TiO₂ nanosheet were prepared by simple hydrothermal method.Then,the precursor samples were subjected to liquid phase reduction at 50?with sodium borohydride?NaBH₄?solution.Thus,a series of oxygen-deficient TiO₂nanosheet arrays samples with an adjustable oxygen vacancy doping concentration were obtained.The oxygen nanocrystalline film showed a remarkably enhanced photocatalytic performance by the methyl orange?MO?degradation under the simulated sunlight.The optimum photodegradation rate was 0.6h^-1,which was 1.5times of the pure TiO₂ nanosheet film photodegradation rate,and the cycle of the experiment showed good stability and reusability.It can be seen that the enhanced photocatalytic performance of the oxygen-deficient TiO₂ nanosheet film is due to the synergistic effect of the orientation of the lamellar morphology and the appropriate oxygen vacancy concentration.The former can effectively increase the redox sites of the photocatalytic reaction of the sample,the latter can broaden its light absorption range and improve the conductivity of photogenerated carriers.2.The nanosheets arrays film of CZTS@TiO₂ p-n heterostructures were successfully designed and prepared on the Ti substrate by a simple two-step hydrothermal method.The results show that the p-type CZTS nanoparticles can be successfully assembled on the n-type TiO₂ nanosheet with vertical orientation to form a three-dimensional distributed p-n heterostructured thin film photocatalyst,which can effectively extend the spectral response,promote photogenerated carrier separation and increase the photocatalytic reaction Specific surface area,and then enhanced the photocatalytic activity.The results of photocatalytic degradation of methyl orange?MO?show that the CZTS@TiO₂ p-n heterostructures nanosheets have obvious enhanced photocatalytic performance under simulated sunlight.Under the same conditions,the photocatalytic degradation rate K can be as high as 1.2 h^-1,which is 6.6 times higher than that of pure TiO₂ nanosheets.In addition,the cyclic experiments showed that the CZTS@TiO₂ p-n heterostructure nanosheet arrays have excellent stability and reusability.Significant photocatalytic properties should be attributed to their vertically oriented nanosheet structures,matching energy levels,the best modification of CZTS nanoparticles,and the built-in electric field on the p-n heterojunction interface.We have reason to believe that the nanosheet arrays of CZTS@TiO₂ p-n heterostructures have an effective application prospect in photocatalytic applications.