在真空度为10-5Pa下的液体电化学-飞行时间二次离子质谱联用技术研究  

Coupled Time-of-Flight Secondary Ion Mass Spectrometry-Electrochemical Analysis of Electrode-Electrolyte Interface at High Vacuum of 10-5 Pa

作　　者：夏海伦 华鑫[1] 龙亿涛[1,2] XIA Hai-Lun;HUA Xin;LONG Yi-Tao(School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China;State Key Laboratory of Analytical Chemistry for Life Science,School of Chemistry and Chemical Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]华东理工大学化学与分子工程学院,上海200237 [2]南京大学化学化工学院生命分析国家重点实验室,南京210023

出　　处：《分析化学》2019年第12期1887-1892,共6页Chinese Journal of Analytical Chemistry

基　　金：国家自然科学基金项目(Nos 21834001,21705046)资助~~

摘　　要：传统电化学检测手段致力于研究电活性物质在电极表面的电子转移过程,却很难获得关于电极-电解质界面分子水平的信息。在分子水平实现电化学氧化还原反应中间体的原位检测,对研究电化学反应机理具有重要意义。本研究以辅酶Q0(CoQ0)在金电极表面的氧化还原过程为研究模型,通过构建可用于高真空环境下使用的微流控电化学反应池,在真空度低于10^-5 Pa环境中实现液体电化学-飞行时间二次离子质谱(ToF-SIMS)联用。CoQ0及池体材料氮化硅在电极击穿前后的ToF-SIMS成像结果表明,此联用技术可用于高真空条件下液体样品的直接检测。由电化学工作站对微流控电化学池中的工作电极施加不同电压后,可检测到CoQ0、CoQ0H2及中间体的存在,其随电压相互转化关系与CoQ0在水溶液中的氧化还原行为一致。CoQ0及其还原产物的质谱信号强度的相对变化情况提供了电极表面CoQ0氧化还原过程的直接分子证据,进一步表明此联用技术在电极-电解质界面原位检测方面具有应用潜力,为电极表面电化学反应机理研究提供了更多信息。Electrode-electrolyte interface, where the electrochemical reaction happens, plays an important role in the investigation of electrochemical mechanism. The traditional electrochemical techniques pay more attention on the charge transfer process happened on the electrode. However, they cannot provide information of the electrode-electrolyte interface at molecular level. How to realize the in-situ electrochemical monitoring of the intermediates on the electrode-electrolyte interface during redox reaction is of great significance to the study of electrochemical mechanism. In this work, electrochemical reaction of coenzyme Q0(CoQ0) on the gold electrode was studied by time-of-flight secondary ion mass spectrometry(ToF-SIMS). A high vacuum compatible microfluidic electrochemical cell was fabricated for the electrochemical study of CoQ0. Then, a micro-hole with diameter of 2 μm was fabricated on the electrochemical cell by the primary ion beam of ToF-SIMS for the subsequent analysis. To evaluate the feasibility of ToF-SIMS for liquid sample measurement, the chemical distribution of CoQ0 and the SiN- around the micro-hole were measured. The stable distribution of CoQ0 and the SiN- during the ToF-SIMS measurement indicated that the microfluidic electrochemical cell was compatible for the in-situ detection of the electrode-electrolyte interface in high vacuum environment(1×10^-5 Pa). Electrochemical behavior of CoQ0 in the electrochemical cell was further studied. The variations of CoQ0, CoQ0H2 and related intermediate at different potentials agreed well with the electrochemical reaction of CoQ0 in aqueous solution, which showed that the direct molecular evidence of the electrode-electrolyte interface was obtained. The direct monitoring of electrode-electrolyte interface by ToF-SIMS revealed the electrochemical evolution on the electrode at molecular level, which was of great potential for the detailed understanding of the electrochemical reaction mechanism.

关 键 词：辅酶Q0 电极-电解质界面 原位电化学检测 飞行时间-二次离子质谱 

分 类 号：O65[理学—分析化学]