Understanding and management of (bi)carbonate salt formation in CO2 reduction electrolyzers for long-term operation stability

Converting carbon dioxide (CO2) into fuels and chemicals is a promising way to make chemical manufacturing more sustainable and reduce greenhouse gas emissions. This project focuses on electrochemical CO2 reduction (CO2RR), a process that uses electricity to turn CO2 from industrial emissions from the air into valuable products. However, the buildup of salts inside the device used for CO2RR is a significant challenge.

These salts clog the device's channels and prevent CO2 from reaching the reaction sites, which can cause the device to fail over time. To address this issue, the project team will study how salts form, move, and accumulate in CO2RR devices under different conditions. Using advanced equipment, investigators will track salt formation and movement in real time by measuring ions and observing the reactions.

This will provide a better understanding of the process and help develop strategies to inhibit salt buildup, such as applying specialized coatings to improve the device's long-term performance. Improving CO2RR technology is important for several reasons: it helps reduce greenhouse gas emissions, strengthens economic competitiveness, and creates jobs.

Additionally, the research will contribute to the advancement of knowledge in electrochemical systems, which could benefit other related technologies. The project will also provide valuable hands-on learning experiences for students, fostering critical thinking and innovation as they prepare to become the next generation of scientists and engineers.

The practical deployment and long-term stability of CO2 reduction reaction (CO2RR) electrolyzers are hindered by salt precipitation within the cathode chamber, which obstructs CO2 diffusion channels, leading to performance degradation and eventual failure. The objective of this project is to develop a fundamental understanding of the mechanisms governing salt migration and formation in CO2RR electrolyzers, and to use this knowledge to devise effective strategies for salt removal, thereby enhancing long-term stability.

This will be accomplished by integrating novel CO2RR reactor designs with in-operando spectroscopic techniques and cation mass balance analysis, conducted under various reaction conditions and interfacial microenvironments. The first step will involve establishing a comprehensive cation crossover monitoring platform, enabling detailed tracking of salt migration, crossover, and formation processes.

This platform will also identify key factors influencing salt formation rates. Next, the project will investigate the primary driving forces behind salt migration from the catalyst-electrolyte interface toward the gas flow channels. Based on these findings, surface coating strategies will be developed for the cathode gas flow channels to enhance salt removal and improve the overall stability of the electrolyzer.

Ultimately, this research will provide critical insights into mitigating stability issues in CO2RR systems and offer solutions that can be applied to other electrochemical processes.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.