A tiny pore-confined solid-liquid interface for in-situ ToF-SIMS electrochemistry of nitrobenzoic acid

Abstract

Electrochemical kinetics of electrode-electrolyte interfaces (EEI) play a significant role in the performance of electrochemical systems. In-situ spectroscopic monitoring of the interfaces during electrochemical reactions was a useful way to provide direct molecular information of EEI evolution, yet a great challenge to be realized due to the incompatibility between the EEI and many analytical techniques. In this work, a tiny pore-confined solid-liquid interface was constructed in-situ by time-of-flight secondary ion mass spectrometry (ToF-SIMS) on a gold-coated SiN membrane which was assembled in a three-electrode microcell in advance. The constructed interface was adopted in combination with ToF-SIMS analysis to monitor the real-time evolution of key species at the EEI during redox reactions of nitrobenzoic acid. As a result, the transformation among nitrobenzoic acid, hydroxyaminobenzoic acid and nitrosobenzoic acid were successfully verified by ToF-SIMS. Besides, the chemical conversion, proton gaining/removing as well as adsorption/desorption of electroactive and inert species during the electrochemical process of nitrobenzoic acid were unraveled. As a result, a full picture of the electro-redox mechanism of nitrobenzoic acid was drawn, demonstrating the capability of the constructed interface for providing detailed molecular evidence for electrochemical reactions.