The world is in a race against time to reduce its carbon footprint—that is, the total amount of carbon-based emissions we put out that often prove detrimental to our planet’s sustainability and survival. We’ve launched and developed several key technologies that can either limit the greenhouse gases that we put out or find a way to keep the greenhouses gases we already have locked away—and this new “artificial leaf” from University of Illinois Chicago (UIC) researchers may be one of our best answers for carbon capture to date.
Well, it’s not a “leaf” per se—it’s moreso a way for us to emulate what happens in a plant that lets it stay alive: converting carbon dioxide (CO2) to energy. Essentially, scientists are trying to recreate the process of photosynthesis, albeit in a more distilled sense. What these UIC researchers have done, however, is quite a novel take on the artificial leaf; they tweaked a design they achieved back in 2019, and managed to improve its performance. The 2019 research was published in the journal ACS Sustainable Chemistry and Engineering; this new take, however, was published in the journal Energy & Environmental Science.
The work by the UIC research team builds upon earlier theoretical designs dating as far back as 2019, which involved a catalyst-coated light absorber—the “artificial leaf,” so to speak—that can convert CO2 into carbon monoxide (CO). This light absorber would then be placed inside a semi-permeable transparent capsule made out of quaternary ammonium resin, which was then filled with water.
The concept goes that when the capsule is heated by light, water evaporates through the membrane of the capsule, which then pulls CO2 from the air. This feeds the light absorber inside the capsule, which then converts CO2 to CO while at the same time converting water to oxygen gas.
Now, this recent study actually had the researchers set out to test their concept using a standard artificial leaf system. They modified the said system with cheap materials, thereby creating a water gradient across an electrically-charged membrane where only one side will ever come into contact with water.
In this setup, the “dry” side will actually be exposed to a dry organic solution; this solution will absorb CO2 coming in, forming bicarbonate ions within the solution. These ions then move across the electrically-charged membrane as the ions are attracted to the positively-charged electrode on the “wet” side of the setup. From there, the water dissolves the bicarbonate ions back into CO2, which can then either be released or harnessed as fuel. The entire process can be sped up by applying an electrical charge through the membrane, speeding up the transfer process.
This setup granted the team a high flux of carbon capture that’s 100 times higher than that of other known systems at the time of writing, while needing less energy than the amount required to power a 1-W LED lightbulb, according to the UIC press release. They also computed the carbon capture to cost roughly US$ 145 per ton of CO2 absorbed.
“Our artificial leaf system can be deployed outside the lab, where it has the potential to play a significant role in reducing greenhouse gases in the atmosphere thanks to its high rate of carbon capture, relatively low cost and moderate energy, even when compared to the best lab-based systems,” said corresponding author and UIC College of Engineering assistant professor of chemical engineering Meenesh Singh.
Singh added: “It’s particularly exciting that this real-world application of an electrodialysis-driven artificial leaf had a high flux with a small, modular surface area. […] This means that it has the potential to be stackable; the modules can be added or subtracted to more perfectly fit the need and affordably used in homes and classrooms, not just among profitable industrial organizations. A small module of the size of a home humidifier can remove greater than 1 kg of CO2 per day, and four industrial electrodialysis stacks can capture greater than 300 kg of CO2 per hour from flue gas.”
References
- Carey, J. (2022, January 27). Stackable artificial leaf uses less power than lightbulb to capture 100 times more carbon than other systems. UIC Today; University of Illinois Chicago. https://today.uic.edu/stackable-artificial-leaf-uses-less-power-than-lightbulb-to-capture-100-times-more-carbon-than-other-systems
- Irving, M. (2019, February 14). Real-world-ready artificial leaf can pluck carbon dioxide out of thin air. New Atlas. https://newatlas.com/artificial-leaf-real-world-ready/58472/
- Lavars, N. (2022, January 28). Novel ‘artificial leaf’ design ups the carbon capture rate by 100x. New Atlas. https://newatlas.com/technology/novel-artificial-leaf-carbon-capture-rate-100x/
- Parmet, S. (2019, February 12). Moving artificial leaves out of the lab and into the air. UIC Today; University of Illinois Chicago. https://today.uic.edu/moving-artificial-leaves-out-of-the-lab-and-into-the-air
- Prajapati, A., Sartape, R., Rojas, T., Dandu, N. K., Dhakal, P., Thorat, A. S., Xie, J., Bessa, I., Galante, M. T., Andrade, M. H. S., Somich, R. T., Rebouças, M. V., Hutras, G. T., Diniz, N., Ngo, A. T., Shah, J., & Singh, M. R. (2022). Migration-assisted, moisture gradient process for ultrafast, continuous CO2 capture from dilute sources at ambient conditions. Energy & Environmental Science, 15(2), 680–692. https://doi.org/10.1039/D1EE03018C
- Prajapati, A., & Singh, M. R. (2019). Assessment of artificial photosynthetic systems for integrated carbon capture and conversion. ACS Sustainable Chemistry & Engineering, 7(6), 5993–6003. https://doi.org/10.1021/acssuschemeng.8b04969
- Sivaram, V. (2018, February 21). The race to invent the artificial leaf. MIT Technology Review. https://www.technologyreview.com/2018/02/21/145353/the-race-to-invent-the-artificial-leaf/
