Time-Of-Flight Secondary Ion Mass Spectrometry.Electrochemical Analysis Of Electrode-Electrolyte Interface At High Vacuum Of 1 X 10(-5) Pa

Electrode-electrolyte interface, where the electrochemical reaction happens, plays an importantrole 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 Q(0) (CoQ(0)) 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 CoQ(0). Then, a micro-hole with diameter of 2 mu m 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 CoQ(0) and the SiN- around the micro-hole were measured. The stable distribution of CoQ(0) 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 x 10(-5) Pa). Electrochemical behavior of CoQ(0) in the electrochemical cell was further studied. The variations of CoQ(0), CoQ(0)H(2) and related intermediate at different potentials agreed well with the electrochemical reaction of CoQ(0) 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.