Synthesis And Gas-sensing Properties Of Metal Element Doped Mesoporous Indium Oxide

In recent years,with the development of modern science and technology,the process of industrialization is accelerating.People's living standards have also gradually improved.At the same time,the environment is also deteriorating increasingly.Therefore,there is an urgent need for people to monitor and control the toxic,hazardous,flammable and explosive gases.As a typical semiconductor gas sensor,metal oxide gas sensors dominates a situation in the research and application duo to its low cost,ease of detection,high sensitivity,fast response/recovery and so on.However,the response of sensor based traditional pure oxide semiconductor no longer satisfies practical applying.Therefore,people have improved the gas-sensing properties of the pure metal oxide semiconductor sensor through a variety of methods,such as metal doping or the synthesis of porous materials.In this paper,mesoporous indium oxide?In₂O₃?semiconductor material were synthesized via nanocasting using ordered silicon dioxide FDU-12 as hard templates and the gas-sensing properties of the In₂O₃ sensor was enhanced by doping different metal elements.Then effects of metal doping,the amount of doping metal and mesoporous structure on the gas-sensing performance of indium oxide were investigated.The main contents are as follows:?1?In_2-x Co_xO₃?x=1%mol,3%mol,5%mol and 7%mol?nanospheres were synthesized via two-step impregnation.The effect of Co doping and amount of Co dopant on the crystal structure,morphology and gas sensing performance of In₂O₃ were studied.The results showed that Co ions entered indium oxide lattice and the doping of Co ions inhibited the growth of In₂O₃ crystals.The doping of Co enhanced the gas-sensing properties of In₂O₃ sensor to ethanol gas significantly.In these doped samples,the In_2-x Co_xO₃ sensor with 3%mol Co exhibited the best gas-sensing properties at 350?.The sensitivity to 100 ppm ethanol was 114 and response/recovery time was 17s/45s;meanwhile the device exhibited good selectivity and stability.?2?In_2-x Ni_xO₃?x=1%mol,3l%mol,5%mol and 7%mol?nanospheres were synthesized via two-step impregnation.The results showed that the grain size ofIn_2-x Ni_x O₃ nanospheres were about 20 nm and the grain size decreased as the amount of doped Ni increased.The doping of Ni enhanced the gas-sensing characteristics of the mesoporous In₂O₃ nanospheres gas sensor to ethanol greatly.The In_2-x Ni_xO₃ sensor with1%mol Ni exhibited the best gas-sensing properties at 350? in those samples.The sensitivity of 100 ppm ethanol gas was 126 and the response/recovery time was 15s/49s;meanwhile the device exhibited good selectivity and stability.?3?In_2-x Fe_xO₃?x=1%mol,3l%mol,5%mol and 7%mol?nanospheres were synthesized via one-step impregnation.The results indicated that surface area of In_2-x Fe_x O₃ nanospheres increased by one-step impregnation.The gas-sensing performances of In₂O₃ sensor were enhanced through the doping of Fe ion significantly.In the four Fe doped In₂O₃ samples,the In₂O₃ sensor with 5%mol Fe showed highest response to ethanol gas.The sensitivity of 100 ppm ethanol gas was 133 and the response/recovery time was 15s/55 s at 350?;meanwhile the sensor exhibited good selectivity to ethanol,but the stability was low relatively.?4?In_2-x Ce_xO₃?x=1%mol,3l%mol,5%mol and 7%mol?nanospheres were synthesized via two-step impregnation.The results showed that the doping of Ce ion not only improved the sensitivity to ethanol significantly,but also accelerated the response rates greatly and lowered the operating temperatures.The optimum operating temperature of In_2-x Ce_xO₃ sensor was 330?.Compared with the optimum operating temperature of pure In₂O₃ sensor,it decreased 20?.The optimal doping amount was 3%mol.The sensitivity to 100 ppm ethanol gas was 146 and the response/recovery time was 14s/40 s at330?.Besides it exhibited excellent selectivity and stability to ethanol gas.Mesoporous In_2-x Ce_xO₃ nanospheres sensor will have potential application value in the detecting ethanol gas.