"Carbon capture technology is a big part of the global strategy to reduce emissions and fight climate change. But the important question of what we do with the captured carbon dioxide remains an open challenge. Do we simply push it underground, or is there more to it? Scientists certainly think so," the team explained.
Researchers are exploring ways to convert captured carbon dioxide into more useful compounds, including green fuels. One promising approach is the reduction of carbon dioxide into formate, a compound that can power fuel cells. However, existing methods require pure carbon dioxide, which involves costly pressurization and results in low conversion efficiency.
To address these issues, reactive carbon capture (RCC) processes have been developed. These processes use bicarbonate solutions instead of pure carbon dioxide, eliminating the need for energy-intensive pressurization. "The key challenge facing researchers here is the design of a better electrochemical cell which can selectively produce formate ions from bicarbonate ions without losing out to side reactions, like the production of hydrogen," the researchers noted.
The research team, led by Professor Fumiaki Amano, has designed a new electrochemical cell that achieves this selectivity. Their design uses a porous membrane made of cellulose ester to separate the electrodes, which are made of catalytic material. Hydrogen ions produced at one electrode pass through an electrolyte membrane into the porous layer, where they react with bicarbonate ions to create carbon dioxide. This carbon dioxide is then efficiently converted into formate ions at the other electrode.
In tests, "Not only does this outperform existing designs, the cell was found to operate smoothly for over 30 hours and realize nearly complete conversion of bicarbonate to formate," the researchers confirmed. The cell demonstrated a faradaic efficiency of 85%, meaning that a significant majority of electrons were successfully converted to formate instead of other compounds. After the water is removed, the resulting product is solid, crystalline formate fuel.
As society strives toward a green transformation, advancements like this could play a key role in improving the efficiency of carbon capture technologies. The researchers are optimistic that their new bicarbonate electrolyzer will become a viable solution for a sustainable future.
Research Report:Highly selective formate formation via bicarbonate conversions
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