Spectro-electrochemical setup for in situ and operando mechanistic studies on metal oxide electrode surfaces

This work shows a combined setup of Diffuse Reflectance FT-IR Spectroscopy (DRIFTS) and electrochemical characterization by AC and DC methods for in situ and operando investigations of surface species during CO₂ electrolysis on metal oxide electrodes and their correlation with electrochemical activity. A high-temperature reaction chamber enables conducting DRIFTS and electrochemical experiments simultaneously at temperatures up to 1000 °C in both reductive and oxidative reaction atmospheres and under anodic and cathodic polarization conditions. A dedicated gas- and electrical feedthrough solution is presented, which is the key element required for recording electrochemical AC and DC characteristics using an electrochemical cell, which is simultaneously studied by DRIFTS experiments under realistic operation conditions. Selected results, obtained on a gadolinium doped ceria model solid oxide electrolysis cell upon different polarization states, demonstrate the basic functionality and capabilities of the setup and show how the simultaneous DRIFT-spectroscopic and electrochemical investigation of the surface and bulk chemistry on electrode materials leads to increased insight in the population of potential intermediates during CO₂ electrolysis. With infrared spectroscopy and impedance spectroscopy as common and complementary spectroscopic methods in material science, the setup is considered to exhibit a huge potential in a wide field of fundamental and applied mechanistic research.