In-situ Raman Observation on Gas Diffusion Electrode/Polyelectrolyte Interface

Abstract

Polyelectrolytes (PEs) serve as the critical medium for electrochemical reactions in membrane-based electrochemical devices, such as fuel cells and membrane electrolyzers. To optimize membrane-based electrochemical device performance and elucidate reaction mechanisms, there is a pressing need for detailed microscopic molecular information at gas diffusion electrode/PE interfaces. In this work, we designed a novel membrane-based-electrochemical-device-like gas diffusion electrode/polyelectrolyte electrochemical in-situ Raman cell. The cell's configuration and gas transfer characteristics closely mimic those of MBEDs under working conditions. We created a Pt/Nafion(s) interface by hot-pressing satellite Au@SiO₂-Pt loaded carbon cloth with a Nafion membrane, and used this interface for electrochemical in-situ surface enhanced Raman spectroscopy (SERS) observation, including oxygen adsorption/desorption processes, structure of interfacial water and functional groups of Nafion under Ar. The cell enables negatively polarize the potential down to -1.6 V vs. RHE without stripping of the solid/solid interface, despite vigorous H₂ generation. The stability of the interface under extreme conditions demonstrates rapid gas transfer at the interface. This observation underscores the potential of our in-situ Raman cell for studying various gas-involved reactions under conditions that closely resemble those in operational MBEDs.