Research On Preparation And Gas Sensing Performance Of Indium Oxide Based Nanomaterials By Electrospinning

With the continuous renewal and change of human production and life style,people begin to pay more attention to their own health and the safety of the living environment,especially to all kinds of toxic and harmful gases that may harm health and damage the atmospheric environment.As a device that can monitor the concentration and composition of various gases,gas sensor has been widely used in many scenes and attracted more people’s attention.Because of a series of advantages of metal oxide semiconductor gas sensor itself,such as relatively good performance,simple device structure and high cost performance,it has become the object of many researchers to report.Most of the time people evaluate the performance of a gas sensor is often based on its sensitivity,but not enough attention to other performance indicators.In fact,the performance of a gas sensor is never determined by a single index.The purpose of this paper is to detect two target gases,namely nitrogen dioxide and triethylamine,and to solve the two problems existing in the gas sensor,one is to accelerate the recovery speed of the room temperature gas sensor,the other is to improve the sensitivity of the gas sensor,the specific research content is as follows:1.One-dimensional In₂O₃ nanowires were synthesized by electrospinning and high temperature calcination.The microstructure of In₂O₃ nanowires was further refined by SEM and TEM.The sensor based on In₂O₃ nanowires shows high response value,low detection limit and good gas selectivity in NO2 gas sensing performance test.However,similar to most NO₂ gas sensors at room temperature,the sensor prepared in this paper has a long recovery time,which makes it difficult to meet the actual requirements,while it has a high response to NO₂.In order to avoid the traditional temperature increase to accelerate the desorption of gas molecules,this paper used the visible light wavelength range of 400-700 nm,and select the appropriate light intensity（4.58 m W/cm²）at the time of sensor began to recover the surface of the light sensor,through the photons to speed up the process of stripping NO₂ molecules,so as to achieve the effect of acceleration sensor,recovery.In the part of mechanism explanation,the reason of the high performance of the sensor is explained by the XPS test results of the material and the O₂-TPD test results of the material.The promoting effect of photons on the molecular desorption of NO₂ is systematically elaborated in detail,so as to accelerate the recovery speed of the sensor.2.α-Fe₂O₃ nanowires with uniform and continuous morphology have been successfully synthesized,and the sensor based onα-Fe₂O₃ nanowires showed higher selectivity to triethylamine gas in several organic volatile gases,but the overall gas sensitivity index is not good.Therefore,In order to improve the gas sensitivity of the sensor,In₂O₃ was introduced into theα-Fe₂O₃ component,and several groups of Fe/In samples with different molar ratios（9:1,4:1,1:1）were prepared,which were named Fe_1.8In_0.2O₃ NWs,Fe_1.6In_0.4O₃ NWs and Fe In O₃ NWs,respectively.The effect of the amount of In₂O₃ on the phase and crystallinity of the material was described by XRD.According to the SEM characterization results,the influence of the addition of In₂O₃ on the overall material can be preliminarily seen from the microscopic morphology.The addition of In₂O₃ makes the component grain size on the surface of the material nanowire become smaller and denser,and the surface of the nanowire becomes smooth gradually.TEM characterization results further confirmed the surface details of Fe_1.6In_0.4O₃ NWs sample,the surface of the nanowire appeared pores.In the subsequent sensor gas sensing performance test,it was found that the sensor based on Fe_1.8In_0.2O₃ NWs,Fe_1.6In_0.4O₃ NWs and Fe In O₃ NWs had different degree of performance improvement compared withα-Fe₂O₃ NWs,including the response value to triethylamine and the response/recovery time.The final results showed that the sensor based on Fe_1.6In_0.4O₃ NWs had the best performance.In the part of explaining the gas sensitivity mechanism,the reason why the gas sensitivity performance of the sensor is improved by adding In₂O₃ is explained by combining the XPS characterization results of several groups of samples,especially the analysis of O_V and O_C contents in the material.