Doping Modification And Gas Sensing Properties Of In₂O₃ Cubic Nanomaterials

With the rapid development of science and technology,the quality of air has attracted more and more attention.However,many polluted gases,especially volatile organic compounds?VOCs?,are easy to diffuse,difficult to detect,and highly toxic.Such gases,even at very low concentrations,can cause immeasurable damage to the human body and pose a great threat to people's normal production and life.Thus,we need to use simple and effective means to monitor this kind of poisonous and harmful gas.Among all kinds of gas sensors,the sensors based on metal oxide semiconductors are widely used in chemical production,life safety,environmental protection,military engineering,medical and health,construction and other fields because of their high sensitivity,fewer samples required,good stability,low cost,fast response,simple test circuit and easy compatibility with semiconductor technology.In this paper,the effects of doping modification and morphology control of In₂O₃ on its gas sensing properties are studied to meet the demand of improving the gas sensing properties of classical materials.In general,the mechanism of doping modification and morphology modification on the enhancement of gas sensitivity of In₂O₃was studied from the following three systems:?1?In₂O₃ micron cubic gas sensing materials doped with Pd with different contents were prepared by hydrothermal process and impregnation method.Through XRD,SEM,XPS characterization and gas sensitivity test,it is found that Pd doping can significantly improve the gas sensitivity of In₂O₃ cubes,which is mainly attributed to the increase of reactive sites and catalytic overflow effect caused by Pd doping.Among them,1 mol%Pd-In₂O₃ has the best ethanol gas sensing performance.Its detection limit for ethanol is as low as 1 ppm,response/recovery time is 2 s/13 s,and its selectivity and stability are good enough to meet the real-time monitoring of ethanol gas.?2?Pr-doped In₂O₃ nanocubes gas sensing materials were synthesized by one-step hydrothermal process and subsequent calcination process.XRD,TEM,BET,XPS characterization tests and gas sensitivity tests of the synthesized materials show that the sensor based on 2 mol%Pr-In₂O₃ has excellent gas sensitivity to triethylamine,including extremely high sensitivity,detection limit as low as 0.2 ppm,excellent selectivity of stability.Its excellent gas sensing performance can be attributed to the large specific surface area and PR doping,which enhance the oxygen vacancy concentration of the material and essentially promote the reaction between the measured gas and the material.?3?In₂O₃ submicron hollow cubes were synthesized by soft template method.XRD,SEM,BET,etc.were used to characterize and test the gas sensitivity of the material.It was found that the material had high sensitivity to ethanol,extremely fast response/recovery time,good stability and selectivity.It was demonstrated that the special morphology and pore structure of In₂O₃ hollow cube had great influence on the gas sensitivity of ethanol,and it was a potential gas sensitive material.The effect of solution p H on the growth of hollow materials was studied,and the possible growth mechanism was given,which provided a feasible strategy for the subsequent synthesis of hollow materials.