Scientists intensify electrolysis, utilize carbon dioxide more efficiently with magnets

"Our ultimate goal is to transform carbon dioxide back into carbon-based chemicals"

02-Jul-2021 - USA

For decades, researchers have been working toward mitigating excess atmospheric carbon dioxide (CO₂) emissions. One promising approach captures atmospheric CO₂ and then, through CO₂ electrolysis, converts it into value-added chemicals and intermediates--like ethanol, ethylene, and other useful chemicals. While significant research has been devoted to improving the rate and selectivity of CO₂ electrolysis, reducing the energy consumption of this high-power process has been underexplored.

In ACS Energy Letters, researchers from the University of Illinois Urbana-Champaign report a new opportunity to use magnetism to reduce the energy required for CO₂ electrolysis by up to 60% in a flow electrolyzer.

In a typical CO₂ flow electrolyzer, electricity is supplied to drive the reactions at the cathode (where carbon dioxide is reduced into useful byproducts) and the anode (where water is oxidized, producing oxygen).

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Most studies have focused on making the reduction reaction at the cathode more efficient at higher rates; however, this process requires little energy compared to the oxidation reaction on the anode--which often accounts for more than 80% of the energy required for CO₂ electrolysis, and therefore, offers the most room for improvement.

"The answer was staring us right in the face--of course, the trick is to reduce the energy consumption at the anode," said first-author Saket S. Bhargava, a graduate student in chemical and biomolecular engineering at Illinois. "We decided that if oxygen evolution is the problem, why not use a magnetic field at the oxygen evolving electrode and see what happens to the entire system."

They used a magnetic field at the anode to achieve energy savings ranging from 7% to 64% by enhancing mass transport to/from the electrode. They also swapped the traditional iridium catalyst--a precious metal--with a nickel-iron catalyst comprised of abundant elements.

"Our ultimate goal is to transform carbon dioxide back into carbon-based chemicals," said lead author Paul Kenis, a chemical and biomolecular engineering professor and department head at Illinois. "With this study, we have demonstrated how further to reduce the significant energy requirements for CO₂ electrolysis, hopefully making this process more viable for adoption by industry."

https://www.chemeurope.com/en/news/1171759/scientists-intensify-electrolysis-utilize-carbon-dioxide-more-efficiently-with-magnets.html