Structural Construction And Gas Sensing Properties Of Indium-based Semiconductor Nanomaterials

With the rapid development of industrial technology,people's awareness of safety and health is increasing,it is urgent to monitor the air quality in all kinds of living and production sites.The detection and monitoring of gas has been widely used in various fields.Therefore,the development of gas detection methods and gas detection equipment has a very good application prospects.Due to the large surface area and high surface activity of metal oxide nanomaterials,many researchers begin to study the metal oxide nano materials for gas sensors.The gas sensor based on metal oxide nano material has high sensitivity,quick response and recovery speed.Indium oxide(In2O3)is an important n-type wide band gap semiconductor,which has excellent optical and electrical properties.In2O3 is often prepared by calcination of the precursor In(OH)3.In(OH)3 is a semiconductor with a direct band gap of 5.15 eV.However,as a semiconductor,most of the previous studies are In(OH)3 good crystallization or morphology,few studies of its practical application.The application of In(OH)3 in photo catalyst and gas sensor has been reported in the literatures.We think that In(OH)3 has a very good application prospect in the gas detector.Based on this,the content of this paper made the following three aspects:(1)The cubic ln(OH)3 with internal porous structure was prepared by hydrothermal method using indium nitrate as indium salt,ammonioformaldehyde(HMT)as precipitating agent.The effect of hydrothermal factors on In(OH)3 gas sensing properties was studied.Analysis of the obtained material and its structure by XRD test,the morphology and microstructure of the obtained materials were tested by SEM and TEM.The formation process of particles is analyzed.Based on the prepared In(OH)3 samples,the gas sensor was prepared.The sensitivity,response time,the lowest detection concentration,and selectivity of the sensor for harmful gases were tested.In(OH)3 was processed to change the conduction type.The gas sensing properties of the induced In(OH)3 were studied.Finally,the mechanism of In(OH)3 conductivity type transformation was proposed based on XPS and in situ FTIR.(2)In2O3 was obtained by annealing treatment of precursor In(OH)3 prepared from hydrothermal method.The structure of the obtained material was analyzed by XRD.And the morphology and microstructure of the obtained materials were tested by TEM.Based on the prepared In2O3 samples,the sensor was prepared.The sensitivity,response time,the lowest detection concentration,and selectivity of the sensor for harmful gases were tested.In2O3 was processed to change the conduction type.The gas sensing properties of the induced In2O3 were studied.Finally,the mechanism of In2O3 conductivity type transformation was proposed based on XPS and in situ FTIR.(3)Preparation of precursor solution by adding PVP into mixed solution of indium nitrate as indium salt and ethanol and N,N-dimethylformamide(DMF)solvent.The composite fiber containing polymer was spun by electrospinning technique,and then through high temperature annealing treatment to get rid of the polymer obtained tubular In2O3 nanofibers.The effects of PVP concentration,spinning voltage and receiving distance on the morphology of nanofibers were studied.Analysis of the obtained material and its structure by XRD test,the morphology and microstructure of the obtained materials were tested by SEM.Based on the prepared In2O3 samples,the sensor was prepared.The sensitivity,response time,the lowest detection concentration,and selectivity of the sensor for harmful gases were tested.The effects of the content of indium on the structure and properties of the final products were investigated.