Study On Formaldehyde Gas Sensor Based On The Nano-materials Of Fe₂O₃/Ag

The concentration of formaldehyde gas sent out by the indoor decoration materials is generally high,which seriously endangers human health,so the concentration of indoor formaldehyde gas monitoring has become a top priority.In order to solve this problem,the nano-materials of Ag-doped Fe₂O₃ were prepared by hydrothermal method and a side heated type formaldehyde gas sensor was further prepared.The sensitivity and response recovery characteristics of the sensor were improved by changing the doping carbon nano-tubes.The main work of this paper is as follows:Firstly,we prepared the Ag-doped Fe₂O₃ nano-materials and their characterization studies.The crystal morphology,grain size and surface performances of the Ag-doped nano-materials were investigated by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,energy dispersive spectrometer?EDS?,F-Sorb2400?BET?and other method.Under the same condition,the results show that Fe₂O₃ doped with Ag has more specific surface area than the pure nano-materials of Fe₂O₃.and with the improvement of Ag doping quantity,specific surface area of the material is increasing.Secondly,we have fabricated Ag-doped Fe₂O₃ nano-materials to produce sintered side-by-side formaldehyde gas sensors for gas-sensing properties.The results show that the Ag-doped Fe₂O₃ sensor has higher sensitivity and better selectivity to formaldehyde.The sensitivity of Fe₂O₃ to formaldehyde gas is the best,when the calcination temperature is600?,the molar ratio of Ag is 6%.At the optimum working temperature of 180?,the sensitivity of the sensor to the volume concentration of 100 ppm formaldehyde is 3.9,the response time is 5min,the recovery time is 3min.The sensor was placed on the AS-20 sensor aging station for 30 days,ageing with continuously.The component's resistance has not changed almost.This suggests that it has an excellent stability.Thirdly,we conducted a gas-sensing performance of formaldehyde gas sensors doped with carbon nano-tubes.The results shown that Fe₂O₃/Ag doped with 5% carbonnano-tubes has the better sensitivity to formaldehyde gas,and at the same time,the response recovery characteristics of gas sensor are improved obviously.The sensor has the best gas-sensitivity to formaldehyde,when the calcination temperature is 600?,and the carbon nano-tube doping amount is 5%.At the optimum working temperature of 180?,the sensitivity of the sensor to the volume concentration of 100 ppm formaldehyde is 6.1,the response time is 3min,the recovery time is 4min.