Preparation And Research Of Semiconductor Gas Sensor Based On Indium Oxide

Due to the rapid development of industrial modernization and the rapid increase of the number of automobiles,the content of NO₂ gas has been increasing continuously in the atmosphere environment.As a typical air pollutant,nitrogen dioxide mainly comes from the exhaust gas in the combustion process,which seriously affects the respiratory system of humans and animals.The increasing attention to environmental protection and human health has attracted the attention of researchers to the high efficiency gas detection.Gas sensors based on semiconductor metal oxides can be tested under different conditions for a variety of coexisting toxic gases,and have many advantages such as non-toxicity,low cost and high stability and so on.Therefore,many researchers and research institutions have focus their attention on this field.The sensing mechanism of gas sensors is based on the chemical reaction between the semiconductor metal oxide and the atmospheric composition.Indium oxide?In₂O₃?is an important n-type semiconductor,which exhibits unique sensing properties for the detection of NO₂ and other gases.However,the gas sensor produced by pure semiconductor oxide material?In₂O₃?has the fatal shortcoming such as long response and recovery time during NO₂ detection.The gas sensitive material can be modified by means of doping and composite.Therefore,this paper aims to improve the sensitivity of semiconductor oxide for NO₂ detection through doping method and fabricate high performance NO₂ gas sensor.The research contents and achievements of this paper are as follows:First,through solvothermal method combined with subsequent calcination treatment,different proportion of Ag doping of hollow sea urchin In₂O₃ microspheres have been synthesized.The structure,composition and morphology were confirmed by XRD,SEM,TEM and BET characterizations.Gas sensing properties of the gas sensor based on those silver doped In₂O₃ were investigated.The experimental results indicate that the response of the gas sensor to NO₂ gas can be obviously increased.The response of the gas sensor based on 1.0 mol%Ag doped In₂O₃materials to 1 ppm NO₂ reach to 190,which is about 23 times higher than that of the sensor without doping,at the optimal working temperature of 62?.Furthermore,the gas sensor based on 1.0 mol%Ag doped In₂O₃ materials have obvious response to 50 ppb NO₂,and the response value is about 3.5.Second,with indium chloride and iron nitrate as the precursor,Fe doped In₂O₃microspheres were obtained through simple hydrothermal method.SEM and TEM characterizations prove that 3D flower-like microspheres hierarchical material is composed of nanosheets.The results of gas sensing investigation indicates that the sensors based on0.5 mol%Fe doped materials have the highest response at the optimal working temperature of 50?.The response to 500ppb NO₂ is about three times higher than that of the gas sensor without doping.Furthermore,the sensor has obvious response to 20 ppb NO₂,and the response value is about 2.2.