高选择性气体传感器的制备及其选择性和气敏机理的探讨

The optical waveguide (OWG) sensor have been attracted widespread interest around the world owing to the potentials for high sensitivity, fast response time, and monitoring at room temperature. As the most important component of OWG, the sensitive layer would directly affect to the selectivity of sensor. In this project, the Lithium Iron Phosphate, Zinc Ferrite, Polyvinyl Pyrrolidone (PVP) will be selected as basic materials, and the composite materials which doped different amount of transition metal and their oxides will be synthesized. The thin film OWG gas sensor and resistance-type gas sensor will be prepare using this composite materials, and compare their gas sensing properties; study the intrinsic link between the change in resistance of the resistance-type thin film gas sensors with the characteristic parameters such as the refractive index, absorption coefficient and transmittance of sensing layer of OWGs. We will analyze the crystal structure, surface morphology, chemical composition, relative contents and optical properties of thin film. The adsorption energy between the sensitive film and the measured gas will be calculated using the Density function theory (DFT). Sum up above studies, we would discuss the selectivity and gas sensing mechanism of optical waveguide sensor, and will summarize the influence of transition metal-metal oxides doping on gas sensing selectivity of basic materials. These studies will provide an experimental data for design of optical waveguide sensing layer, and contribute to promote the development and industrialization of optical waveguide gas sensor.

光波导传感器具有灵敏度高、响应快和室温下操作等优点，在国际上受到广泛关注。敏感层作为其重要组成部分直接影响传感器的选择性。本项目以磷酸亚铁锂、铁酸锌和聚乙烯吡咯烷酮等材料为基体，掺杂过渡金属及其氧化物，合成不同配比的复合材料；拟制备复合薄膜光波导气体传感器和电阻型薄膜气体传感器并比较它们的气敏特性，探讨电阻型薄膜气体传感器电阻变化与光波导气体传感器敏感层的折射率，吸收系数和透光率等特性参数之间的内在联系。对薄膜的晶体结构、表面形貌、掺杂物种类、相对含量及光学特性进行表征和分析。通过密度函数方法计算出敏感膜与被测气体之间的吸附能量。综合以上研究探讨光波导气体传感器的选择性响应和气敏机理；总结掺杂过渡金属及其氧化物对传感器选择性响应的影响。这些研究将为光波导气体传感器敏感层的设计提供实验数据，并有助于推动光波导气体传感器的开发和产业化。

敏感层作为光波导（OWG）传感器的重要组成部分,将直接影响其传感性能。本项目以磷酸亚铁锂、铁酸锌和聚乙烯吡咯烷酮（PVP）等纳米薄膜作为敏感层，通过掺杂过度金属及其氧化物或其它材料，研制了气敏薄膜/玻璃光波导和电阻型（厚膜）气敏元件；对薄膜的晶体结构、表面形貌、化学成分及相对含量进行表征和深度分析；探讨了敏感薄膜的处理方法和金属的掺杂对其结构、物相、光学性质及气敏性的影响。.利用敏感薄膜（NiO）和几种挥发性气体分子的结构，采用密度函数方法（DFT）计算了敏感膜的吸附能量；结果显示：氯苯气体分子在NiO表面镍原子上的吸附结构较稳定，这与NiO薄膜OWG元件的检测结果完全一致。.Ag-Y共掺杂的LiFe1-0.01xY0.005x Ag0.005x PO4薄膜（未热处理）OWG元件和电阻型气敏元件对甲醛气体具有非常高的选择性响应，但在不同温度（450℃）热处理后对二甲苯和氯苯等气体有较大响应；分别掺杂Ni，Pt，Ti、Cr、Zn和共掺杂这些元素的LiFe0.99M0.01 PO4薄膜OWG元件都对二甲苯、氯苯和苯乙烯等有较大响应。Ni和Pt分别掺杂LiFe0.99M0.01 PO4的电阻型气敏元件对二甲苯、氯苯和苯乙烯等气体有较大响应。十二烷基苯磺酸纳中均匀分散LiFePO4纳米颗粒研制OWG元件也对苯乙烯、二甲苯和氯苯等气体有较大的响应。.通过溶胶凝胶和液相法合成制备的ZnFe2O4及其掺杂NiO，V2O5的薄膜OWG元件和电阻型气敏元件都对H2S和二甲苯有较大的选择性响应；.综合以上实验数据，采用同种敏感材料制作的OWG与电阻型气元件对同种气体显示出选择性响应；根据这个结果可以推测：半导体气敏薄膜/玻璃光波导气体传感器的选择性及气敏机理与电化学气体传感器相似。.同样筛选了间甲酚紫、偶氮苯和溴百里酚蓝等指示剂与PVP、硬脂酸等聚合物复合，研制了高选择性和高灵敏度的OWG传感元件，并检测到体积比浓度低于1×10-13（2.62×10-7 mg/m3）SO2气体和（2.41×10-7 mg/m3）三甲胺气体。.项目的研究成果已得到了国内外同行专家的认可与肯定，在国内外重要学术刊物上已发表16篇学术论文，其中SCI收录3篇，会议论文9篇，已培养了1名博士和10名硕士研究生。