Researchers have developed a simple method to address long standing issues in the carbon dioxide reduction reaction (CO₂RR) paving the way for simpler more effective CO₂RR carbon capture systems.
CO₂RR is a relatively new carbon capture method which uses electricity and catalysts to convert carbon dioxide gas into useful carbon containing compounds. CO₂RR relies on membrane electrode assembly (MEA) electrolyzers for the carbon dioxide conversion, however, over time these systems accumulate bicarbonate crystals on the cathode gas diffusion electrodes. These salts block the flow of carbon, leading to reduced performance and the eventual failure of the system.
While reducing the overall amount of cations in the electrolytes did prove effective at reducing the bicarbonate buildup, the teams true breakthrough came after observing droplets in the system which contained the carbonate crystals. While these carbonate crystals were initially trapped in the droplets, over time the droplets would evaporate leaving behind the carbonate crystal deposits.
Based on this observation, the team decided to coat the channels of the electrolyzer in parylene, a synthetic polymer which repels water. Their findings, which are published in Nature Energy, demonstrate that after applying the parylene coating, the electrolyzer gas channels flushed out significantly more cations than those of an uncoated system. By flushing out excess cations, the team reported a notable increase in electrolyzer stability.
“Currently, salt-crusted electrodes and other affected components of the MEA electrolyzer need to be replaced after a few hundred hours of run time, but with our improvements, the functional stability of this device can be extended to more than 1,000 hours,” said Haotian Wang, associate professor in chemical and biomolecular engineering at Rice University. “We are excited by this significant improvement in the device’s performance and life, and we believe that the easy scalability of these solutions to commercial applications will drive wider adoption of CO₂RR technology as a means to manufacture chemicals and combat climate change.”