原位电化学-质谱联用研究液/液界面上无金属卟啉催化氧还原反应机理

氧还原反应是生物膜界面上的重要反应和生物呼吸过程中的关键环节，液/液界面上卟啉催化的氧还原反应可以看作最简单的生物膜界面氧还原反应模型，研究该类反应对于模拟生物膜上的呼吸链反应过程以揭示其反应机理具有重要意义。然而，无金属卟啉作为催化剂参与的液/液界面氧还原反应研究相对较少，特别是其反应机理目前仍不明确，主要的问题和困难在于：现有电化学和光谱分析方法无法提供中间体的化学组成和结构信息，并且实验中无法检测到氧还原反应可能生成的产物水以验证是否存在4H+/4e−还原过程，所以尚缺乏直接的实验证据来阐明具体的催化循环和反应机理。本项目拟发展和应用基于凝胶杂化超微电极技术的原位电化学-质谱方法，检测和识别氧还原反应过程中的关键短寿命中间体，以系统研究并揭示液/液界面上不同种类无金属卟啉催化氧还原反应机理，建立氧-18同位素气体标记的原位电化学-质谱联用分析新方法并拓展该方法的应用研究范围。

The oxygen reduction reaction (ORR) is a critical reaction at biofilm interfaces and a key link in the process of biological respiration. ORRs catalyzed by porphyrins at liquid/liquid interfaces (L/L) can be regarded as the simplest model of ORRs at biofilm interfaces. Studying ORRs at L/L is significant for simulating the respiration chain reaction on biofilms to elucidate its reaction mechanism. However, ORRs catalyzed by metal-free porphyrins at L/L were rarely studied, and particularly their reaction mechanisms are still unclear. The main problems and difficulties are as follows: The existing electrochemical and spectroscopic analytical methods cannot provide the chemical composition and structural information of the intermediates. Moreover, the product water that could be generated in ORRs cannot be detected in these experiments to verify the existence of the 4H+/4e− reduction process. Therefore, it still lacks direct experimental evidence to clarify the specific catalytic cycle and reaction mechanism of ORRs catalyzed by metal-free porphyrins at L/L. This project aims to develop and apply the in situ electrochemical mass spectrometry (EC-MS) based on gel hybrid ultramicroelectrodes to detect and identify key short-lived intermediates in ORRs, to systematically study and reveal the reaction mechanism of ORRs catalyzed by different kinds of metal-free porphyrins at L/L. This project will establish a new method for oxygen-18 gas labeling analysis by in situ EC-MS and expand the applied research scope of this method.