Preparation Of Tetrapod Zinc Oxide Heterostructure And Its Application In Environmental Field

In this paper,a kind of tetrapod zinc oxide was primarily prepared according to evaporation by heating zinc powder in a simple muffle furnace.On this basis,firstly,in a facile dip-calcination method,a layer of moss-like zinc ferrite(ZnFe2O4)nanoparticles was grown on the surface of the tetrapod zinc oxide(ZnO-T),and then a two-/three-dimension(2D/3D)architecture was obtained.On account of rich porosity,which is conducive to the circulation of gas,thus promoting the absorption of active gas,it is very suitable for gas detection for this unique structure.The results of gas sensing experiments show that the structure is very sensitive to hydrogen sulfide gas(H₂S,2 ppm,250?,65%RH).The response time and recovery time are 2 s and 9 s,respectively.Even the concentration of H2S is as low as 0.6 ppb,it still has a high sensitivity.Moreover,there is a certain selectivity and repeatability to detect hydrogen sulfide gas for the structure of ZnFe2O4/ZnO-T.Based on the energy band structure,it is concluded that the heterojunction between ZnFe2O4 and ZnO-T;the tetrapod network structure;the catalytic action of ZnFe2O4 and ZnO-T are the three main reasons for the improvement of gas sensitivity of ZnFe2O4/ZnO-T.Secondly,a ternary heterostructure composited of molybdenum disulfide/zinc sulfide/zinc oxide(MoS2/ZnS/ZnO-T)was prepared by a hydrothermal method.The photocatalytic degradation experiments were carried out by simulating the sunlight of Xenon lamp and organic dye wastewater of methylene blue aqueous solution.The results show that the degradation efficiency of MoS2/ZnS/ZnO-T for methylene blue aqueous solution(15 mg/L)can be reached to 87%,and the first-order degradation rate is 4.22 times that of ZnO-T.According to the active species trapping experiment,the cavity rooting in the structure of MoS2/ZnS/ZnO-T has played a major role in the photocatalytic degradation.The crystal structure of the sample does not change after three cycles of degradation,indicating its good stability.Interestingly,a mechanism of double type ? heterojunction reaction is proposed based on the capture experimental results and the band structure of each component of the material.Finally,a heterostructure of copper oxide/zinc oxide(CuO/ZnO-T)was also synthesized by the dip-calcination method.The morphology and composition were characterized by Scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS),and so on.The potential applications of this structure are also preliminarily discussed in this paper.