Analysis of Mass Flows and Membrane Cross-over in CO₂ Reduction at High Current Densities in an MEA-Type Electrolyzer

Abstract

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Investigating Electrode Flooding in a Flowing Electrolyte, Gas‐Fed Carbon Dioxide Electrolyzer

“…Although this work focuses on Ag‐GDEs in contact with a flowing alkaline electrolyte for CO 2 ‐to‐CO conversion, we anticipate that persistent cathode alkalinity will broadly impact the performance of both liquid‐ and solid‐electrolyte systems. For example, current‐accelerated parasitic uptake of CO 2 has been reported for membrane‐based CO 2 electrolysis systems with both weak carbonate electrolytes or deionized water fed to the anode. Polymer electrolytes feature immobile cation moieties that facilitate anion (i.e., OH − , HCO 3 − , and CO 3 2− ) transport and remove the need for the mobile alkali metal cations (e.g., Na + , K + , Cs + ) responsible for the salt precipitation that diminishes the effectiveness of GDEs in flowing electrolyte devices.…”

High carbonate ion conductance of a robust PiperION membrane allows industrial current density and conversion in a zero-gap carbon dioxide electrolyzer cell

“…from OH À in a CO 2 rich environment. 28,29 This observation suggests that a membrane with high carbonate/bicarbonate conductivity is a prerequisite for high current density AEM CO 2 electrolysis. This might seem counter-intuitive, as carbonate conduction leads to reactant loss to the anode, which on the system level invokes extra costs associated with the regeneration of the anolyte, and/or CO 2 separation/loss from the anode gas.…”

Insights into the carbon balance for CO2 electroreduction on Cu using gas diffusion electrode reactor designs

“…Thus, the measurement of outlet gas flow in high-rate CO2 reduction plays an important role in calculation of Faradaic efficiency (FE) of gas products. However, currently the majority of work in high-rate CO2 electroreduction [21][22][23]28,[31][32][33][34][35][36] have not explicitly stated that their Faradaic efficiency calculations were based on the outlet gas flow from their reactor (exception for few research on CO2 reduction to CO 37,38 ). Therefore, to ensure results are not errantly reported in GDEs-type electrolyzers, it is critical to fundamentally understand the carbon balance and benchmark the evaluation of the catalytic selectivity (or FE) at high current densities.…”