Synthesis Of ZnO Functional Material And Their Application In Photoelectrochemical Sensing

In recent years,zinc oxide（ZnO）has been widely studied in nanometer applications.It is an n-type direct semiconductor with a wide band gap which is about 3.37 e V.Its exciton binding energy is 60me V at room temperature.Because of its good photoelectric properties,it is widely used in the field of photoelectric.However,its wide band gap determines that it can only respond photoelectrically to ultraviolet light with a wavelength of less than 400 nm,which greatly limits its use of visible light with a large energy ratio.Due to its high exciton binding energy,photo-generated electrons and holes are easily annihilated in the body and cannot move to the surface of the material,resulting in a decrease in quantum efficiency.These shortcomings of ZnO limit the application of ZnO in photoelectric.Therefore,in order to increase the carrier lifetime of ZnO and improve its photocatalytic ability,we have adopted methods such as surface modification,multiple recombination and enrichment of oxygen vacancies.The main research work of this paper has the following aspects:Using the hydrothermal method prepared the base material of ZnO porous nanosheets formed by the accumulation of nanoparticles on the FTO,and characterize and test the crystal structure,morphological characteristics,optical properties of the sample and its ascorbic acid test performance.At the same time,the formation process of ZnO porous nanosheets was briefly analyzed and the mechanism of photocatalytic degradation.The research results showed that zinc oxide alone has limited use of sunlight and its low carrier lifetime,resulting in poor photoelectric response and photocatalytic performance.Using Se^2-to replace O^2-in ZnO prepared ZnSe by in-situ substitution method to form a ZnO/ZnSe heterojunction,then coating the prepared Au particles on the surface of ZnO/ZnSe prepared ZnO/ZnSe/Au multi-element composite material.The effect of changing the time conditions of the Se^2-substitution reaction on the structure,morphology and properties of the ZnO/ZnSe/Au multi-element composite.And the growth mechanism and photocatalytic degradation mechanism of ZnO/ZnSe/Au was briefly discussed.Research indicates,ZnSe is a very suitable material for forming type II heterojunction with ZnO.Using the narrow band gap semiconductor material ZnSe,an Au/ZnSe/ZnO heterojunction was constructed to obtain a wide light absorption range,high carrier lifetime and high catalytic activity photoelectric sensor.The Au particles were introduced to enhance the overall conductivity of the material performance and catalytic ability,as a carrier transfer layer to improve the overall stability of the material.And ZnSe will also play multiple roles in the photoelectric process:first,it formd a type II heterojunction with ZnO to promote the separation of carriers;second,it improved the absorption of visible light by ZnO materials and increased the light absorption range;third,it improved the recombination impedance of the carrier interface of the material hinders the recombination of electrons and holes and improved the carrier lifetime.ZnO nanorod arrays were prepared on FTO by seed method,and the effects of sintering under different atmospheres on the photo-electrochemistry of ZnO nanorod arrays were compared.Studies had shown that,compared with non-burning and atmospheric sintering,the photoelectric response of the ZnO nanorod array after nitrogen sintering was stronger,and its carrier lifetime was also significantly increased.This was mainly due to the nitrogen sintered ZnO nanorod array.The concentration of oxygen vacancies is significantly increased,leading to the local energy level formed by the band gap of the sample,which improved the photoelectric response ability of ZnO,and promoted the separation of carriers and extend the lifetime of carriers.