Research Of Ethylene Gas Sensor Based On WSe₂/rGO And ZnO/CNFs Composite Membrane

Ethylene（C₂H₄）is an important plant hormone,and its emission can be used as an indicator to detect the maturity of fresh fruits and vegetables.At present,the most commonly used technologies for C₂H₄ detection are chromatography and spectrum,but these detection technologies have disadvantages such as high cost,large size,or long detection time,and their application is limited in the agricultural field.The chemical resistance sensor has advantages of small size,high sensitivity and low cost,which is expected to meet the real-time detection demand of C₂H₄ in the future of agriculture.Due to the limited chemical activity of C₂H₄ molecules,its detection is relatively difficult.At present,the detection of C₂H₄ gas by chemical sensors is mostly performed at high temperature,which causes greater energy consumption and safety problems.In this paper,two chemical resistance gas sensors are designed and prepared,which can detect C₂H₄gas at room temperature.The specific research contents are as follows:1.Tungsten selenide/reduced graphene oxide（WSe₂/r GO）composite thin membrane gas sensor was fabricated on cross finger electrode by gas spraying and self-assembly,combined with thermal reduction process.For 100 ppm C₂H₄ gas test,the response of WSe₂/r GO sensor prepared by gas spraying method is about 2 times better than that by self-assembly method.To analyze the reason,WSe₂/r GO composite membrane prepared by the self-assembly method has a layered structure,while the WSe₂/r GO composite membrane prepared by the gas spraying method overlaps the r GO nanosheets and WSe₂nanosheets.The overlapping structure is not only beneficial to the transmission of electrons between different materials,but also increases the specific surface area,and increases the adsorption site of gas molecules.In addition,the experiment also compared the gas sensing performance of the single layer membrane and composite membrane prepared by gas spraying method.For 100ppm C₂H₄ gas test,compared with single r GO and WSe₂ sensor,the response of WSe₂/r GO composite membrane sensor improved about3 times.At the same time,the sensor also exhibits faster response/recovery time,better repeatability,selectivity and lower detection limit（≤5ppm）.2.Porous zinc oxide/carbon fiber（1-Zn O/CNFs）composite membrane sensor was prepared by electrospinning and heat treatment process,with zeolite imidazole ester framework structure material（ZIF-8）as precursor and polyacrylonitrile（PAN）as main polymer material.The performance of the 1-Zn O/CNFs sensor was compared with Zinc oxide/carbon fiber（2-Zn O/CNFs）composite membrane sensor prepared by zinc acetate as precursor.The morphology characterization results show that:compared with pure carbon fiber,the 1-Zn O/CNFs and 2-Zn O/CNFs composite fiber morphology is more regular and the adhesion is reduced;At the same time,organic groups in ZIF-8decomposed at high temperature,resulting in a large number of pores on the surface of 1-Zn O/CNFs composite fiber,which increases the specific surface area of the material.Gas sensor results show that:for 100ppm C₂H₄ gas,the response of the 1-Zn O/CNFs is about11%,which is 3.5/1.8 times higher than that of pure carbon fiber and 2-Zn O/CNFs,and has a faster response/recovery time（138s/59s）and better repeatability.At the same time,the sensor also shows a lower detection limit（≤10ppm）and better selectivity.