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

Electrode-electrolyte interface, where the electrochemical reaction happened, played an important role in the electrochemical mechanism investigation. The traditional electrochemical techniques paid more attention on the electron transfer process on the electrode but provided limited information of the electrochemical evolution at molecular level. Realizing the in-situmonitoring of the intermediates at the electrode-electrolyte interface during the redox reaction was essential for the study of electrochemical mechanism. In this work, electrochemical reaction of coenzyme Q0(CoQ0) on gold electrode was investigated 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, which realized the in-situdetection of the electrode-electrolyte interface in high vacuum environment (10−5Pa). The variations of CoQ0, CoQ0H2and related intermediate at different voltages agreed well with the electrochemical reaction of CoQ0in aqueous solution. The direct monitoring of electrode-electrolyte interface by pre-confined ToF-SIMS could reveal the electrochemical evolution on the electrode at molecular level, which was of great potential for the detailed understanding of the electrochemical reaction mechanism.