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基于室温离子液体的电导型气体传感器
【作者】 李冬梅；
【导师】 王荣；
【作者基本信息】 上海师范大学 ， 分析化学， 2009， 硕士
【摘要】 气体传感器在环境监测、工农业生产控制、军事及医学等领域均具有广泛的应用前景。由于离子液体具有可忽略的蒸汽压,高的热稳定性等独特的物理化学性质,可作为一种新型的气体敏感材料。本工作围绕研制基于室温离子液体的电导型气体传感器位研究重点,分别研究了不同有机溶剂对离子液体电导率的影响;传感器制作工艺优化及性能测试;以及不同离子液体制成的传感器阵列的可行性。并得到了一些初步的结果:1)本文成功合成1-丁基-3-甲基咪唑六氟磷酸盐(BmimPF6)和1-丁基-3-甲基咪唑四氟硼酸盐(BmimBF4)离子液体。2)考察了有机溶剂的加入对离子液体导电率的影响。有机溶剂的加入使得离子液体的导电率增大;不同的有机溶剂对不同的离子液体的电导率具有不同的影响;相同浓度下,极性大的有机溶剂对离子液体的电导率影响较大。同时考察了温度对离子液体电导率的影响,结果表明离子液体的电导率随温度的升高而升高,但随所含有机溶剂浓度的增加,其变化率基本与温度无关。3)制作了以离子液体BmimPF6为敏感膜的电导型气体传感器,测试了这种传感器的性能,并对其测试条件如温度、工作频率等及传感器的制作工艺进行了优化。同时考察了它对水蒸汽及有机蒸气的响应,并利用支持向量机算法对传感器的响应值与蒸气理化性质参数之间的关系进行了建模分析。实验结果发现基于室温离子液体的传感器具有结构简单、稳定性高及线性范围宽、可重复利用等优点。这种传感器可重复使用超过一个月的时间。4)运用计时阻抗的方法测试了不同有机蒸气在5种不同离子液体敏感膜传感器中的响应,实验结果发现不同的有机蒸气对不同的离子液体制成的传感器具有不同的响应信号:BmimPF6这种离子液体对乙酸乙酯蒸气的响应最大;EmimCF3SO3对异丙醇的响应最大,对二氯甲烷的响应最小,相对其他离子液体EmimBF4对其他有机蒸气的吸收都比较好。随着对功能化室温离子液体研究的进一步深入,必然能为提高气体传感器的选择性提供更多的可能性。
【Abstract】 Gas sensors have attracted many attentions due to their potential applications in environment protection, mass production control and clinic diagnosis etc. One of the hot points in the studies of gas sensors is to find out the new sensing material. Ionic liquids are the liquids at room temperature which contain essentially only ions. The ionic liquids show high ionic conductivity, low vapor pressure, low combustibility, excellent thermal stability, a wide liquid range, and favorable solvating properties for diverse compounds, which might be used as a new kind of gas sensing material. This thesis focused on developing a new kind of conductivity gas sensors based on ionic liquid. Several interesting results as shown in follow were obtained.1. ) Two ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) and 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4) were successfully synthesized.2.)The influence of trance impurity on the conductivity of ionic liquids was investigated. Results suggested that the conductivity of the ionic liquid increased with the increasing of the concentration of the organic solvents in it, and the influence by the polar solvents is greater than that by nonpolar solvents. In addition, though the conductivity of ionic liquids increased with the temperature increasing, but the influence of the same impurity at different temperature are almost the same.3.)A novel gas sensor using room temperature ionic liquid, BmimPF6, as the sensing material was proposed based on the increasing of the ionic conductivity of BmimPF6 when it was exposed in humid or organic solvent vapor. This mple-structure sensor showed a good stability and wide linear range for humidity or organic solvent vapor detection. By chemometrics, the relationship between the impedance response of the sensor towards different kinds of saturated organic solvent vapors and the physicochemical property constants of the organic solvents was also studied.4.)Five different kinds ionic liquids were used for construct the gas sensors. These sensors showed quit different sensitivity toward the organic vapors. For example, the sensor using BmimPF6 showed largest sensitivity towards ethyl acetate, while which using EmimCF3SO3 showed largest sensitivity towards isopropanol. Such results suggested the possibility of using different ionic liquids to design sensor array for the Enose system.