| As a common atmospheric pollutant,NO2 is the main cause of acid rain,photochemical smog and fine particulate matter(PM 2.5).CO is a toxic gas without color and irritating odor,which is one of the main components of coal gas used in life and industrial production.It is also one of the most widely distributed pollutants in the atmosphere.These two pollutant gases have a serious impact on human production and life.Therefore,it is necessary to develop high-performance gas sensitive materials that can effectively detect NO2 and CO gas for improving air quality and ensuring sustainable development.As a semiconductor material with wide bandgap,low resistance and high thermal stability,I112O3 has shown a good application prospect in the detection of harmful gases.At present,the hydrothermal method mostly used in the laboratory to synthesize metal oxide semiconductor has a low efficiency,which limits the research and industrial application of semiconductor gas sensors.In the paper,hollow sphere structured InOOH and Zn(OH)2/InOOH precursor suspension was prepared by a composite soft template method and atmospheric reflux method,rod-like In(OH)3 precursor suspension was prepared by atmospheric reflux method.Subsequently,hollow sphere In2O3,ZnO/In2O3 and rod-like In2O3 submicron materials with the high specific surface area were obtained through heat treatment.Finally,the morphology and structure of obtained materials were characterized.Gas sensing performances were investigated,and gas sensing mechanism was analyzed.The details were shown as following:(1)Hollow sphere In2O3 submicron materials were prepared by a composite soft template method and atmospheric reflux method,and the effects of heat treatment temperature on the NO2 gas sensing performances of InmO3 submicron materials were analyzed.The prepared In2O3 was hollow sphere structure,which was formed by the accumulation of nanoparticles.There were some In2O3 particles and clusters on the surface and gap of hollow spheres,and they decreased with the increase of calcination temperature.The optimum working temperature of hollow sphere In2O3 sensor was 63?.Compared with other sensors,the hollow sphere In2O3 sensor treated at 400? had the highest response,which could reach 127.8 to 500 ppb NO2 gas at 63?.The analysis of the full width at half maximum shown that the higher the crystallinity of powder,the lower the response of hollow sphere In2O3 sensor to NO2 gas.(2)Rod-like In2O3 submicron material was prepared by atmospheric reflux method Compared with the composition,morphology and gas sensing properties of hollow sphere In2O3 materials,the effects of morphology on the gas sensing performances of In2O3 submicron material were analyzed.The In2O3 materials prepared by atmospheric reflux method was submicron rod structure,which formed by the accumulation of nanosheets,and these rods were dispersive.The optimum operating temperature to NO2 gas of rod-like and hollow sphere In2O3 sensor was 63?,and rod-like In2O3 sensor exhibited higher gas sensitivity,which was caused by specific surface area and voidage.(3)Based on the preparation of hollow sphere InOOH,2nO/In2O3 submicron composites were prepared by secondary atmospheric reflux method.The effect of the ratio of In2O3 to ZnO on the gas sensing perfoemances of ZnO/In2O3 composites was studied.A high solid solution ratio was formed between In2O3 and ZnO.The optimum operating temperature of ZnO/In2O3 sensor to CO gas was 175?.Compared with the other five sensors,15Zn/In sensor had the highest response,which could reach 16.03 to 500 ppm CO gas at 175OC,and the response-recovery time was 13 and 260 s,respectively.Finally,ZnO/In2O3 sensor showed a good selectivity to CO gas. |
PDF Full Text Request