Fabrication And Properties Of Acetone Gas Sensors Based On LnFeO₃

Acetone(CH₃COCH₃)is a volatile organic compound(VOC)gas that seriously harms people's lives and health.The traditional acetone gas sensors have the disadvantages of low response value,poor stability and long response/recovery times.Therefore,research and development of high-performance gas sensors for detecting acetone gas is an important task to be solved urgently.In this work,the effect of lanthanide on the gas sensing performances of LnFeO₃(Ln=Yb,Tm and Er)nanocrystallines are investigated.The correlation mechanism between the light illumination and the gas-sensing properties of the material is studied through the light field adjustment means of different wavelengths.The main work of this paper is divided into the following two aspects:1.LnFeO₃ nanocrystallines are prepared by sol-gel method and the crystalline structure,morphologies and elemental composition are characterized by X-ray diffraction(XRD)and field-emission scanning electron microscope(FE-SEM).LnFeO₃ nanocrystallines are made into the heating gas sensors and their gas sensing properties are tested in different test conditions.The experimental results reveal that the gas sensor based on Yb FeO₃nanocrystalline exhibited the best response ability and selectivity toward acetone gas compared with Tm FeO₃ and ErFeO₃ based gas sensors.The Yb FeO₃ nanocrystalline gas sensor exhibits rapid response/recovery characteristic(18/25 s,10 ppm acetone)and the response value can be 4.23.Besides,the detection limit can reach to be 500 ppb of Yb FeO₃ gas sensor.2.In order to overcome the defects of conventional gas sensors,such as low selectivity and long response/recovery times,light-assisted LnFeO₃ nanocrystallines gas sensors are designed by introducing light fields with different wavelengths(?=365-660 nm).Through experimental comparison,compared with the dark environment,the best operating temperature of the LnFeO₃ nanocrystallines gas sensors is reduced from200?to 170?under ultraviolet light and visible light field.And under the light fields,the response/recovery times and the selectivity toward acetone gas of the gas sensors are improved.At the 170?operating temperature,it is found that with the assistance of ultraviolet light at 365 nm,the response value of Yb FeO₃ nanocrystalline gas sensor reaches 5.2 toward 10 ppm acetone,and its response/recovery times are 9 s and 8 s,respectively;With the assistance of blue light at 530 nm,the response value of Tm FeO₃nanocrystalline gas sensor reaches 4.6 toward 10 ppm acetone,and its response/recovery times are 11 s and 9 s,respectively;With the assistance of ultraviolet light at 365 nm the response value of ErFeO₃ nanocrystalline gas sensor reaches 4.1toward 10 ppm acetone,and its response/recovery times are 10 s and 9 s,respectively.The improvement of gas sensitivity performance of LnFeO₃ nanocrystallines gas sensors are ascribe to the increase of activation energy on the surface of LnFeO₃nanocrystallines under the irradiation of ultraviolet and visible light.