Preparation Of SnO₂ Based Nanomaterials And Research On Their Gas Sensitivity

As a typical gas in air pollution,NO₂ is the main factor causing some natural disasters such as acid rain and smog weather,causing serious harm to human life and health.Therefore,it is of great significance to develop a gas sensor that can detect NO₂.The metal oxide semiconductor sensor（MOS）can effectively detect NO₂ gas.Compared with other gas sensors,it has the advantages of simple fabrication,sensitive gas response,and good selectivity.SnO₂ has the advantages of high electron mobility,good chemical and thermal stability,etc.,which has been widely used in the field of metal oxide semiconductor sensors.However,the current research shows that SnO₂,as sensitive material,still has defects such as high working temperature,long response and recovery time in the process of gas detection.Based on the above defects,this paper will design SnO₂ nanomaterials to improve its defects in gas detection and improve gas sensing performance.The specific research contents are as follows:（1）Two-dimensional porous nanosheet-structured SnO₂ nanomaterials were prepared by solvothermal method and by adjusting the heat treatment temperature.The gas-sensing properties of the materials were explored,and the results showed that the optimal working temperature of the three groups of SnO₂ nanomaterials was 100℃under the condition of ultraviolet light excitation.And the comparison of the response values shows that the response value of the sample prepared when the heat treatment temperature is 600°C is 1100 at 100°C for 20 ppm NO₂,the response and recovery time are 38 s and 23 s,respectively,and the detection limit is 100 ppb.The response values for other gases are much lower than NO₂,indicating that the sample has excellent selectivity to NO₂.At the same time,the gas-sensing test results of this sample also show that the samples prepared at 600℃have good repeatability and long-term stability.This work realizes the detection of NO₂ gas at a lower working temperature（100℃）.（2）In order to improve the gas sensing ability of pure SnO₂ nanomaterials to NO₂ at room temperature,In₂O₃/SnO₂ composites（In₂O₃/SnO₂-1、In₂O₃/SnO₂-2、In₂O₃/SnO₂-3）were prepared by solvothermal method.The gas-sensing properties of the composites were investigated.The results showed that the working temperature could be reduced to room temperature under the excitation condition of ultraviolet light.The response value of In₂O₃/SnO₂-2 to 50 ppm NO₂ was the highest at 49,the response time is 8 s,and the recovery time is 17 s and detection limit is 200 ppb.The response value to NO₂ is also higher than other gases,and it also has excellent repeatability and long-term stability.By preparing In₂O₃/SnO₂ composite materials,the response value of pure SnO₂ nanomaterials for detecting NO₂ at room temperature was successfully improved,and the response and recovery time were shortened.（3）In order to improve the gas-sensing responsiveness of SnO₂ nanomaterials to NO₂ at the working temperature without adding light and at room temperature,RGO/SnO₂ composites（0.5-RGO/SnO₂,1-RGO/SnO₂,3-RGO/SnO₂,5-RGO/SnO₂）were prepared by solvothermal method.The gas-sensing properties of the composite at room temperature were tested,and the results showed that the gas-sensing response value of 1-RGO/SnO₂ to NO₂ was higher than that of pure SnO₂ nanomaterials,and the response value of 20 ppm NO₂ at room temperature without adding light is 19,the response time is 27 s,the recovery time is 42 s,and it has good selectivity and long-term stability for NO₂ at room temperature.