钙钛矿电化学反应器净化柴油车尾气污染物的原位表征与机理探索

Electrochemical exhaust gas purification using the pervoskite electrochemical reactor is a new technology under development for simultaneous removal of nitrogen oxides, excess hydrocarbons and particulate matter from diesel engine exhaust. The development of this technology is hindered by a lack of knowledge about the processes occurring on the electrodes in the electrochemical reactor during operation. In the proposed project, the aim is to identify the reaction mechanisms occurring during electrochemical exhaust gas purification on the perovskite electrode. This will be done by employing Electrochemical Impedance Spectroscopy (EIS) combined with Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS) to monitor the electrode processes in situ from molecular level. An EIS-SHINERS nano-thin-film electrochemical cell will be designed and fabricated in order to perform the EIS-SHINERS characterization on the active reaction zone，which is confined to the region tens of nanometers from the interface between the electrode and electrolyte. The novel approach of studying electrochemical exhaust gas purification in situ with EIS-SHINERS will be combined with conventional electrode studies by X-ray Fluorescence (XRF), Atom Force Microscopy(AFM) etc. This combination of measurements will clarify how the compositional and structural change of the interface affects the electrode processes, how the surface modification promotes the electrode reaction, and how the electrodes activate/degrade. The results of this project will give an in-depth understanding of the electrochemical exhaust gas purification on the perovskite electrode, which will facilitate the future development of pervoskite electrochemical purification reactor with better activity and selectivity.

基于钙钛矿反应器的电化学尾气净化是一种新兴的柴油车尾气后处理技术，可在一种反应器中实现氮氧化物、碳氢化合物和颗粒物多种污染物的协同处理。然而，对电极反应机理认识的不足制约了该技术的发展。本项目拟采用电化学阻抗谱技术（EIS）结合壳层隔绝纳米粒子增强拉曼光谱技术(SHINERS)，对钙钛矿反应器的尾气净化反应开展原位表征和机理探索。通过对壳层隔绝纳米粒子的调控优化和纳米薄膜反应器的构造设计，建立适用于电化学尾气净化的原位表征方法，实现从分子水平对钙钛矿电极数十纳米限域反应活性区的现场分析，并结合X射线荧光光谱(XRF)、原子力显微镜(AFM)等手段，研究电极界面分子在净化反应过程中的成分结构特性和传质传荷行为，构建电极界面特性与反应过程的关系，明确表面修饰的作用机制和活化/衰减的本质原因，从而揭示钙钛矿电极的净化反应机制，为净化器的性能提升提供理论指导，促进电化学尾气净化技术的发展。

近年来，我国雾霾频发，空气质量的急剧恶化使整个社会深切感受到大气污染治理的重要性和紧迫性。发展高效的柴油车尾气净化技术，对改善我国大气质量意义重大，同时蕴含着广阔的应用前景和巨大的经济效益。电化学净化技术是一种新兴的柴油机尾气后处理技术，净化过程仅使用电能，不需任何附加还原剂，避免了二次污染风险、车载管理困难以及燃油效率损失等问题。限制电化学净化技术实现商业化突破的主要瓶颈在于净化器电极的活性和选择性有待提高。实现对电极净化反应过程的现场分析，揭示其反应机理是电化学尾气净化领域一个亟待解决的重要课题。本项目开发了一种具有高灵敏性，高耐热性，无基底选择性的高温表面增强拉曼光谱(SERS)分析方法，并联合电化学阻抗谱表征(EIS)对对电化学净化电极的反应机制进行了原位解析。本项目利用嵌入式纳米核壳结构实现了拉曼增强结构的耐热稳定性，高灵敏性和基底普适性，从而能够应用于高温及复杂尾气环境下电极界面的原位研究。本项目以钙钛矿氧化物为电极材料，制备了全陶瓷电化学净化电池，对陶瓷钙钛矿电极的电化学净化过程进行了系统表征，确定了影响脱硝性能的关键电极过程。本项目分析了表面修饰对钙钛矿电极界面特性和电化学行为的影响规律，明确了表面修饰对电极过程的影响机制，提出了钛矿电极性能演变的内在原因。本项目对电化学净化反应的机制解析及全陶瓷净化装置的探索可为新型电化学尾气处理系统的开发提供理论信息和借鉴意义。本项目在执行期间共发表SCI论文6篇，申请中国发明专利一项，培养硕士研究生3名。