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Carbon Capture System Turns CO2 Into Electricity and Hydrogen Fuel (newatlas.com)
Researchers at Ulsan National Institute of Science and Technology (UNIST) and Georgia Tech have developed a new system that absorbs carbon dioxide and produces electricity and useable hydrogen fuel. New Atlas reports: The new device, which the team calls a Hybrid Na-CO2 System, is basically a big liquid battery. A sodium metal anode is placed in an organic electrolyte, while the cathode is contained in an aqueous solution. The two liquids are separated by a sodium Super Ionic Conductor (NASICON) membrane. When CO2 is injected into the aqueous electrolyte, it reacts with the cathode, turning the solution more acidic, which in turn generates electricity and creates hydrogen. In tests, the team reported a CO2 conversion efficiency of 50 percent, and the system was stable enough to run for over 1,000 hours without causing any damage to the electrodes. Unlike other designs, it doesn't release any CO2 as a gas during normal operation -- instead, the remaining half of the CO2 was recovered from the electrolyte as plain old baking soda. The research was published in the journal iScience.
Reading a bit more (I am not a chemist):
"Because the potential of cathodic reaction is closely influenced by the pH of aqueous solution, the dissolution of CO2 renders a favorable electrochemical reaction environmentby acidifying the aqueous solution."
"Thus, notably, this combined cathodicreaction not only utilizes CO2 to generate H2 but also possesses highly efficient reaction kinetics,possibly overcoming the key issue of sluggish discharge rates for common metal-air batteries."
Figure 4 shows this is a rechargeable battery!
"On repeating the discharge-charge process, the cathode potential profile(Ecathode) presents discharging and charging plateau, clearly proving that this system is rechargeable."
"To confirm the reversibility of hybrid Na-CO2cell, the anodic charge profile (electrolysis profile) was observed. Because Na is one of the most abundant elements on earth, Na metal anode could be easily recycled through a charging process in Na-ion-containing aqueous solution, such as seawater. Figure 4A shows an oxidation rotating disk electrode profile for examining whether CO2 was reproduced during the charging process. Generally, the charging process is regarded as the opposite reaction of the discharging reaction. In this work, however, the generated H2 gas from the discharging process is naturally removed on the surface of electrode, and thus the oxidation reaction proceeds as the oxygen evolution reaction (OER) from the water oxidation (Equation 6).
2H2O -> O2(g) + 4H+ + 4e- Eo= 1.229 V"
As this equation does not involve Na, I'm still unclear on how they are regenerating their Na.
Help! Is there a chemist in the house?
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Sell it to NASA.
They've been looking for ways to get rid of captured CO2 for decades. If you can use it to generate electricity too, I'm sure they'll be interested.
Much more likely though - this requires an input (the sodium?) that will cost more to source than you'll ever save.