Operando Topography and Mechanical Property Mapping of CO2 Reduction Gas-Diffusion Electrodes Operating at High Current Densities

Electrochemical atomic force microscopy (EC-AFM) enables measurement of electrode topography and mechanical properties during electrochemical reactions. However, for aqueous-based reactions that make gas products, such as CO2 reduction and water splitting into CO/H-2, current densities below 1 mA cm(-2) have been necessary to prevent formation of bubbles at the electrode; such bubbles can stick to the AFM probe and prevent further AFM imaging. Here, we demonstrate a novel cell design with a gas-diffusion electrode (GDE) to exhaust the gas products, thereby enabling high current density EC-AFM measurements at 1, 10, and 100 mA cm(-2) that are not disturbed by bubble formation at the electrode surface. These experiments revealed a stable morphological structure of Cu catalysts deposited on GDEs during high current density operation. Systematic spatially resolved maps of deformation and adhesion showed no signs of a gas-liquid interface between catalyst particles of the GDE.

Automated summary

The study demonstrated a novel cell design with a gas-diffusion electrode to exhaust gas products, enabling high current density EC-AFM measurements without interference from bubble formation. It revealed a stable morphological structure of Cu catalysts deposited on GDEs during high current density operation, with no signs of a gas-liquid interface between catalyst particles.