| In recent years,the application of gas sensors in the detection of environmentally harmful gases and human exhaled gas markers has increased.Traditional inorganic metal oxide semiconductor gas sensors have shortcomings such as high working temperature and high energy consumption,which limit their application in low power consumption and portability.Therefore,the development of gas sensors that work at room temperature,low energy consumption and high response has become A research hotspot in this field.In this paper,polyaniline(PANI)and tungsten trioxide-polyaniline(WO3-PANI,W-P for short)gas-sensing materials were prepared respectively,and room temperature gas-sensitivity performance of ammonia and acetone,which are common in the human body's breath due to diseases and harmful gases in the environment,was studied.The gas sensors of polyaniline(PANI)gas-sensitive film materials acidified with dilute HCl at different concentrations were prepared by chemical polymerization.The HCl concentrations were 0.5 mol/L,1 mol/L,and 2 mol/L.The material composition and shape characterization were carried out,and the gas sensitivity of these sensors to acetone was studied at room temperature.Comparing the three materials,it is found that the PANI-1acidified with 1 mol/L HCl has less nano-particle agglomeration,large specific surface area,and the best gas sensitivity response.The PANI-1 sensor was used to conduct a series of gas sensitivity tests on NH3 at room temperature,and it was measured that it has a good gas sensitivity response to 1 ppm ? 1000 ppm NH3,and the response to 1 ppm NH3 reached 1.6,which can be used for environmentally harmful gas NH3(approximately 48 ppm)and medically exhaled NH3(approximately 1.5 ppm ? 15 ppm)in patients with renal failure.The test results show that the PANI gas sensor has good selectivity and repeatability to NH3;when the ambient temperature is 25 ? and the humidity is 40 %RH,the response of PANI to NH3 reaches the maximum.Combined with the material characterization and gas sensitivity test results,the NH3 gas sensitivity mechanism of PANI was analyzed.Tungsten trioxide(WO3)is prepared by hydrothermal synthesis,and WO3 powder and PANI powder are fully ground and mixed to obtain tungsten trioxide-polyaniline(WO3-PANI)composite gas-sensitive material.The ratios of WO3 and PANI are 0:1(pure PANI),1:1,10:1,50:1,100:1,200:1,400:1,500:1,1000:1,and 1:0(Pure WO3).The material composition and shape characterization were carried out,and the gas sensitivity of these sensors to acetone was studied at room temperature.After n-WO3 and p-PANI compound,the W-P composite exhibits p-type semiconductor characteristics.The response to acetone first increases and then decreases with the increase in the proportion of WO3 in the material,and W-P(100:1)has the highest response to acetone.The W-P(100:1)composite sensor was used to conduct a series of gas sensitivity tests on acetone at room temperature.It was measured that it had a good gas sensitivity response to 10 ppm ? 200 ppm acetone,and the response to 10 ppm acetone was1.03.It can be used for the detection of environmentally harmful gas acetone(about 150 ppm)and exhaled acetone(about 21 ppm)in severe diabetic patients.The test results show that the W-P composite sensor has good selectivity and repeatability for acetone;when the ambient temperature is 25 ? and the humidity is 40 %RH,the response of W-P to acetone reaches the maximum.Combined with the material characterization and the gas sensitivity test results,the acetone gas sensitivity mechanism of W-P composites was analyzed. |
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