Preparation And Gas Sensing Properties Of Macroporous ZnO-based Composites

With the rapid development of industry,while bringing convenience to people’s lives,the problem of environmental pollution has become increasingly prominent.In order to detect various toxic and harmful gases in the air,gas sensors emerge as the times require.Triethylamine（TEA）is a colorless organic compound,which is widely used in some industrial production fields,but the steam of TEA is toxic and harmful to the human body,and there is a risk of explosion in case of high temperature and flame,so the development of an effective sensors for monitoring TEA have great application prospects.Metal-oxide-semiconductor gas sensors are the most widely used gas sensors in the world due to their high sensitivity,fast response and recovery speed,and low cost and easy fabrication.As one of the earliest n-type semiconductor sensor materials discovered,ZnO is widely used in many fields such as solar cells,lasers and sensors due to its unique physical and chemical properties.In this paper,ZnO nanomaterials with macroporous structure were synthesized by template method,combined with various experimental methods such as impregnation,vacuum filtration and calcination,and gas sensors were prepared based on this as a matrix for gas sensing testing of TEA.The gas sensing properties of ZnO to TEA were improved by compounding metals,constructing p-n heterojunctions and n-n heterojunctions,and the sensitization mechanism was discussed.1.Using polystyrene colloidal crystals as template and H₂PtCl₆·6H₂O as Pt source,macroporous ZnO-based composites（Pt-ZnO）modified with different Pt contents were prepared by impregnation,vacuum filtration and subsequent calcination.The gas sensitivity test results show that the Pt-ZnO composite with 0.3wt%Pt has the best gas sensitivity,and its response to TEA（6000）is 170 times that of pure ZnO sensor（34）at the optimal operating temperature of 220℃.Moreover,the response speed（16 s）is significantly higher than that of pure ZnO sensor（52 s）.At the same time,the Pt-ZnO sensor has good response repeatability,stability and selectivity to TEA gas.2.Using polystyrene colloidal crystals as template and Ni（NO₃）₂·6H₂O as Ni source,macroporous ZnO-based composites（NiO-ZnO）modified with different contents of NiO were synthesized by impregnation method,vacuum filtration,and subsequent calcination treatment.The gas sensing test found that the NiO-ZnO sensor with a NiO content of 1wt%had the best sensing performance for triethylamine gas,and its optimum operating temperature（180℃）was lower than that of pure ZnO（200℃）.At 180°C,compared with the pure ZnO sensor,the response value is increased from 31 to 207,and the response time is also shortened from 82 s to 12 s,and it has good repeatability,stability and selectivity.3.3.Using polystyrene colloidal crystals as template and SnCl₄·5H₂O as Sn source,macroporous ZnO-based composites（SnO₂-ZnO）modified with different contents of SnO₂were synthesized by impregnation method,vacuum filtration,and subsequent calcination treatment.The research results of gas-sensing properties show that the gas-sensing properties of macroporous ZnO are effectively improved by compounding SnO_2.When the molar percentage of SnO₂is 1%,the SnO₂-ZnO sensor has the best sensing response to triethylamine gas.The response value（450）of SnO₂/ZnO-1 sensor to TEA at 200℃is 10times higher than that of pure ZnO sensor（42）,which improves the sensitivity of ZnO sensor to TEA,but the response time（89 s）is lower than that of ZnO sensor（76 s）has increased,and has good repeatability,stability and selectivity in the detection of TEA.The paper contains 43 figures,10 tables,and 120 references.