Development of a Modular Operando Cell for X-ray Imaging of Strongly Absorbing Silver-Based Gas Diffusion Electrodes

Abstract

Metal-based gas diffusion electrodes are utilized in chlor-alkali electrolysis or electrochemical reduction of carbon dioxide, allowing the reaction to proceed at high current densities. In contrast to planar electrodes and predominantly 2D designs, the industrially required high current densities can be achieved by intense contact between the gas and liquid phase with the catalytically active surfaces. An essential asset for the knowledge-based design of tailored electrodes is therefore in-depth information on electrolyte distribution and intrusion into the electrode's porous structure. Lab-based and synchrotron radiography allow for monitoring this process operando. Herein, we describe the development of a cell design that can be modularly adapted and successfully used to monitor both the oxygen reduction reaction and the electrochemical reduction of CO2 as exemplary and currently very relevant examples of gas-liquid reactions by only minor modifications to the cell set-up. With the reported cell design, we were able to observe the electrolyte distribution within the gas diffusion electrode during cell operation in realistic conditions.

When Flooding Is Not Catastrophic─Woven Gas Diffusion Electrodes Enable Stable CO2 Electrolysis

“…As the electrical potential is changed, the electrolyte probably transitions to a Wenzel wetting state , by spreading along the uncoated, conductive carbon domains. The understanding of electrowetting in carbon-based GDEs could be greatly improved by future studies with operando synchrotron imaging. ,, …”

“…The understanding of electrowetting in carbon-based GDEs could be greatly improved by future studies with operando synchrotron imaging. 48 , 50 , 51 …”

“…The understanding of electrowetting in carbon-based GDEs could be greatly improved by future studies with operando synchrotron imaging. 48,50,51 We would like to distinguish the reversible, physical electrowetting effect from irreversible (electro-)chemical degradation, which can decrease the contact angle of susceptible GDL materials such as the Freudenberg H23C6 permanently. 33 This GDL substrate undergoes electrochemical degradation at cathode potentials below −0.65 V versus RHE.…”

Operandocharacterization of continuous flow CO2electrolyzers: current status and future prospects

“…These are focused on the membrane hydration, water distribution across the MEA and gas bubble formation in the electrolyte layers. 78,91,100,128,129 To maintain a high ionic conductance, therefore fast ion transport in CO2 electrolyzers, it is necessary for the ion exchange membrane to be in a well-hydrated state. 31 Recently neutron imaging was employed to directly quantify liquid water distribution across a MEA (Figure 11A).…”

“…A modular cell for X-ray radiographic imaging of electrolyte distribution in strongly absorbing Ag GDEs was reported recently. 129 Electrolyte intrusion into and distribution within the GDE was observed for ORR and CO2RR. For the CO2RR studies, a cell with AEMseparated anolyte and catholyte chambers was employed.…”