Strategies for the mitigation of salt precipitation in zero-gap CO2 electrolyzers producing CO

Abstract

Salt precipitation in the cathode gas diffusion electrodes of zero-gap CO₂ electrolyzers producing CO is a major challenge to the stability and durability of this technology. In this review, we examine different strategies proposed in the literature for mitigating salt precipitation in anion-exchange-membrane-based zero-gap cells. We discuss the advantages and limitations of these approaches, with a focus on material developments and systemic approaches. By normalizing all data to the cumulative amount of converted CO₂, we provide a quantified comparison and recommendations for future development. Our review shows that material developments, such as the use of hydrophobic or superhydrophobic coatings, can effectively reduce salt precipitation, but may not be suitable for long-term operation due to their limited durability. Systemic approaches, such as adjusting the operating conditions or incorporating salt removal methods, can also be effective in mitigating salt precipitation, but may come with additional cost and complexity. Overall, our results suggest that a combination of these approaches may be the most effective in achieving the long-term stability and durability required for commercialization.