Research On Performance Optimization Of ZnO-based Gas Sensor

Development and environment are mutually compatible,which is a prerequisite for achieving sustainable development.Unrestricted or inappropriate development will cause serious damage to the ecological environment,which will not only restrict a country’s economic development and social development,but also pose a serious threat to human health.Alcohol gases such as ethanol（C₂H₅OH）,n-propanol（C₃H₇OH）and n-pentanol(C₅H₁₁OH)as a common class of volatile organic compounds,are widely used in the organic synthesis process used as solvents and extractants.Vapors or mists of alcohol gases not only cause irritation to eyes,skin and respiratory mucous membranes,but also may cause headache,dizziness,difficulty in breathing,nausea,vomiting and other symptoms.Humans who have been in or suddenly placed in an atmosphere of high concentrations of alcohol gases for a long time may suffer from diplopia or even methemoglobin leukemia in severe cases.Therefore,achieving accurate detection of alcohol gases is of great importance in terms of human health.There are various methods to detect alcohol gases,and compared to other large detection instruments,gas sensors have been widely investigated for their low cost,small size,integratability,and ability to achieve real-time monitoring.Among them,oxide semiconductor gas sensors have shown great potential for the detection of alcohol gases due to their low lower detection limit and all-solid-state nature.By modulating the micro and nano structure of oxide semiconductor materials,doping and modification of oxide semiconductor materials,the specific surface area,oxygen vacancy content and forbidden band width can be changed to improve the performance of oxide semiconductor gas sensor devices.In this paper,we optimize the gas sensing characteristic of ZnO-based gas sensors by using the n-type oxide semiconductor ZnO as the sensing material and achieving the adjustment of the electronic distribution of ZnO by adjusting the heating rate during the sintering of ZnO and doping the ZnO,the main work is as follows:1.ZnO nanoflowers with a diameter of about 6μm,which are three-dimensional structures composed of porous nanosheets,were prepared by a hydrothermal method.The gas sensing characteristic test results of the sensor was enhanced by varying the temperature rise rate during sintering of the ZnO sensitive material.The response of the ZnO nanoflower to 100 ppm n-pentanol at 300°C was 22.1 for the ZnO nanoflower with a temperature rise rate of 5°C min^-1at sintering,and 5.1 and 3.9 for the ZnO nanoflower with a temperature rise rate of 1°C min^-1and 10°C min^-1at sintering,respectively.the enhancement of the gas-sensitive performance can be attributed to the fact that the temperature rise rate at sintering changed the response of the ZnO nanoflower sensitive material surface adsorbed oxygen content.2.Ce doped ZnO nanoflower sensitive materials were prepared using hydrothermal method.The gas sensing characteristic test results of the sensor was enhanced by varying the atomic molar ratio of Ce and ZnO.The gas-sensitive test results showed that the response of Ce/ZnO nanomaterials with 3%atomic molar ratio of Ce and ZnO（3at%Ce/ZnO）to 100 ppm n-propanol was found to be 28.1 at300°C,which is about four times higher than the response of undoped ZnO（7.1）.and showed good reproducibility.