Gas Diffusion Electrode with Microporous Layers of Hydrophobicity Gradient Distribution for CO₂ Electrolysis in a Zero-Gap Electrolyzer Operated with Pure Water

Differential Pressure Across a Gas Diffusion Electrode Controls Efficiency of Liquid-Fed Electrolyzers for CO2 Electroreduction at Elevated Temperatures

“…The uppermost layer is in direct contact with an electrolyte or an ion-conducting membrane, establishing the so-called triple-phase boundary (TPB), where the reaction takes place. GDLs are specifically designed to align this boundary accurately with the CL, through variations in hydrophobic additives, thickness, porosity, etc. − Even-though the electrochemical reaction is more likely to take place at a two-phase boundary in the liquid phase, the use of GDEs leads to a very thin liquid layer, resulting in a diffusion path so minimal that we will still refer to it as a TPB in this study …”

“…The cumulative effect of these aforementioned changes results in the displacement of the TPB further into the GDE structure, with ultimately a detrimental outcome for the performance of a liquid-fed electrolyzer. The displacement inevitably leads to the so-called flooding of the CL, which results in increased HER and less eCO 2 RR. ,− Various strategies are proposed in the literature to address this issue, such as altering the composition of hydrophobic species in the MPL, ,,, adding organic additives on the CL, , augmenting the amount and/or type of buffering species in the electrolyte, , increasing the (back) pressure at the gas side of the GDE, , etc. All of these measures will (in)­directly restore the location of the TPB at the CL instead of within the bulk of the GDE, reversing the adverse effect of elevating the temperature.…”