A team of researchers has developed a new, more energy-efficient way to convert CO2 captured from the air into CO—a common component in the production of everyday materials.
In their study, published in Joule, the team lays out their innovative method, which would enable a more feasible pathway for repurposing CO2 captured through technologies like direct air capture (DAC) into value-added products.
One of the conventional methods that enables the utilization of the captured CO2 is electrified reactive capture, where the carbon dioxide is absorbed in an alkali carbonate solution and put through an electrochemical treatment that converts it into CO while also regenerating the capture medium.
While effective, this process is also energy-demanding, which prompted the research team to try and find a more energy-efficient alternative.
To that end, the scientists examined how to increase the activity in bicarbonate electrolysis toward CO, testing a scenario in which the electronic environment was boosted with a cobalt-based catalyst, which resulted in a lowered energy need for activating the CO2 conversion path.
The catalyst was then grafted covalently onto a conductive CO2 nanotube support with the help of amine linkages, which optimized the charge transfer and reaction kinetics.
From there, the research team proceeded by introducing an electrified pH-downshifter to this system, which was done to increase the CO2 availability in the reactive capture phase.
This work resulted in a process of bicarbonate electrolysis to CO, which uses significantly less energy than the conventional process, requiring a full-cell voltage of 2.7 V (100 mA cm−2), as opposed to the traditionally needed full-cell voltage of > 3.7 V.
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As a result, this optimized process also provides 70% faradaic efficiency, enabling an energy intensity of 35 GJ/ton CO, a notable cutback from the traditional need for more than 59 GJ/ton CO.
By operating in ambient conditions, this novel system offers a simplified and modular process for converting atmospheric CO2 to concentrated CO.
Read more: Rice University Tackles DAC Energy Consumption With New Solution
