Study On The Preparation,Structure Regulation And Application Of Metal Oxide Semiconductor Core-shell Heterostructure

The oxide semiconductor materials which represented by ZnO,TiO₂ and SnO₂have good chemical stability,biocompatibility,electrochemical activity and electrical transport characteristics.They have great potential in the fields of optoelectronics,electrochemistry,magnetism and catalytic chemistry.The core-shell heterostructure is a kind of composite structure with special properties by surface modification and coating growth of the core material.In particular,one-dimensional oxide core-shell nanorod arrays have many unique physical and chemical properties,which are different from single structure.They are widely concerned in the field of photocatalysis,photoelectric sensor and solar cell.In this paper,ZnO/zinc titanate and ZnO/SnO₂ core-shell heterostructures were constructed based on ZnO nanorod arrays.Through structural optimization and modification,the effects of the structural parameters and doping concentration on the photocatalytic and UV detection performance of core-shell structure were further studied,and the corresponding physical mechanism was also explored.The specific research contents are as follows:?1?the ZnO nanorod arrays prepared by hydrothermal method were used as a template and then liquid phase deposition method was used to prepare the ZnO/zinc titanate nanorod arrays.The effects of deposition time and annealing temperature on the surface morphology and crystal structure of ZnO/zinc titanate core-shell nanorod arrays were studied.It is found that the amorphous TiO₂ shells were converted to zinc titanate shells at annealing temperature over 600?,and the crystal phases of the zinc titanate shell were changed with the reaction time.The relationship between the structural parameters of ZnO/zinc titanate core-shell nanorod arrays and photocatalytic performance under UV light irradiation was further studied.Moreover,the photocatalysts prepared in this work could be easily recycled and retained stable photocatalytic activity for multiple reuse,and the corresponding photocatalytic mechanism was also explored.?2?N doping of ZnO/zinc titanate core-shell nanorod arrays was carried out by microwave nitrogen plasma.The effects of plasma treating time on the crystal structure,N doping concentration and optical properties of the core-shell nanorod array were studied.It is found that with the increase of plasma treating time,zinc titanate shell gradually transform from Zn₂TiO₄?cubic?phase to ZnTiO₃?hexagonal?phase,and at the same time the concentration of substitutional doping N atoms increases.The optical absorption edge of the ZnO/zinc titanate core-shell nanorod arrays also moved to visible light region,and the absorbance increased significantly.The relationship between nitrogen plasma treating time and the visible light photocatalytic performance of ZnO/zinc titanate core-shell nanorod arrays was further studied.?3?A metal-semiconductor-metal?MSM?UV detector based on ZnO/Zn₂TiO₄core-shell nanorod arrays was prepared and its UV detection performance was also studied.It is found that the Zn₂TiO₄ shell can effectively improve the sensitivity and the response and recovery speed of the UV detector.?4?ZnO/SnO₂ core-shell nanorod arrays were prepared by liquid phase deposition.The effects of annealing temperature on the crystal structure of ZnO/SnO₂core-shell nanorod arrays were studied.The ultraviolet detector based on ZnO/SnO₂core-shell nanorod arrays was prepared,and a comparative study of the ultraviolet detection performance of the detector was conducted.The results show that,compared with ZnO nanorod arrays,nanocrystalline SnO₂ shell can effectively improve the sensitivity of the device.The rise and decay time of the device were significantly reduced.The responsivity of the detector was as high as 4.653A/W at 5 V bias.It can be attributed to the effective inhibition of deep level defects and surface states by nanocrystalline SnO₂ shell.