基于磷灰石型硅酸镧电解质和纳米敏感电极的电流型NOx传感器

Gasoline engine operating in lean burn region can effectively decrease exhaust gases emission and increase heat efficiency, but NOx storage/reduction catalyst is needed in order to remove NOx. However, NOx removal by catalyst storage and the catalyst regeneration process require to be monitored by NOx sensors, so it is very important to develop NOx sensor based on solid electrolyte which can meet above requirments.In this proposal, a planar amperometric NOx sensor will be fabricated based on apatite lanthanum silicate electrolyte and nano-structured sensing electrodes prepared by infiltration technology. The research work includes:(1)Effect of multi-elements doping in the Si sites in lanthanum silicate by wet chemical methods on its phase purity,conductivity and sinterability will be studied;(2) Route of preparation of nano-structured sensing materials and compatability between electrolyte and sensing electrode will be investigated;(3)Investigating into effect of composition and microstructure of sensing materials and micro-structure of three-phase boundary on sensors performance,the sensing fuction design and sensing performance tuning of the sensor will be realized; (4)Sensing mechanism and influential factors for sensor properties will be addressed and sensitivity, response rate, anti-interference ability and long-term stability for the sensor will be improved.By proposed research work,some scientific problems involving in preparation and sensing behavior of the NOx sensors will be solved. Some results with our own copyright will be achieved. The results will lay a solid foundation for industrial application of the NOx sensors.

汽油机在稀薄燃烧运行可有效降低污染物排放，提高热效率，但需"吸藏还原催化剂"来解决NOx的去除问题。而该催化剂对NOx脱除和再生过程必须由在线NOx传感器控制，因此开发可满足上述要求的NOx传感器就变得极为迫切。本研究以磷灰石型硅酸镧氧离子导体为电解质，以浸渍法获得的纳米结构材料为敏感电极，制备平面电流型NOx传感器。拟研究：（1）湿化学法合成硅酸镧的工艺，探索过渡金属硅位多取代对其相纯度、电导率和烧结性能的影响规律；（2）浸渍技术原位制备纳米结构敏感材料的工艺，以及敏感材料与电解质的化学相容性；（3）敏感材料组成，微观结构，三相界面结构等对传感器性能的影响，实现敏感功能的设计和调控；（4）传感器响应机理及其性能影响因素，实现其在灵敏度、响应速度、抗干扰和长期稳定性等方面的提高。通过研究，解决在传感器制备和响应中的一些科学问题，取得一些自主产权成果，为实际应用奠定基础。

汽油机在稀薄燃烧条件下运行可有效提高燃料燃烧效率，降低污染物排放。但产生的大量NOx需“吸藏还原催化剂”来去除。而催化还原脱除NOx的过程和催化剂的再生过程必须由在线NOx传感器控制，因此急需开发可满足上述要求的固体电解质基NOx传感器。本项目采用固态反应法或湿化学法制备了几种磷灰石型硅酸镧氧离子导体，研究了不同元素在La位或Si位取代对其相纯度、烧结性能、微观结构和电导率的影响。筛选出了几个烧结性能好、电导率高的材料体系，其电导率提高了2-5倍，离子迁移数大于0.99。研究了浸渍技术原位制备纳米结构敏感材料的工艺，获得了最佳制备条件。研究了敏感材料与磷灰石型硅酸镧电解质的化学相容性。以具有双层结构的上述氧离子导体为电解质，以原位制备的纳米结构材料为敏感电极，组装了平面电流型NOx传感器及阻抗谱型NOx传感器。探讨了传感器响应机理，以及敏感材料组成，微观结构，三相界面结构等对传感器性能的影响，实现了其在灵敏度、响应速度、抗干扰和长期稳定性等性能的提高。通过研究，初步弄清了在传感器制备和响应中的一些关键科学问题，解决了一些技术瓶颈，取得一些自主产权成果，为传感器的工业应用奠定了扎实基础。将上述思想和方法进行延伸和扩展，本工作还成功地制成了新型NH3传感器，取得了满意结果。本项目实施过程中，发表相关期刊论文23篇，获得河北省自然科学奖三等奖1项（2014），培养研究生11名。