'Artificial Leaf' Design can Increase Carbon Capture Rate by 100 Times

Replicating the natural photosynthesis process, in which plants convert sunlight, water, and carbon dioxide into energy, has long been a scientific ambition. In this regard, a study was published in the journal Energy & Environmental Science.

Often referred to as "Artificial Leaves," these systems have the potential to play a critical part in the fight against climate change, and a group of engineers has now set the bar even higher with a solution that gathers carbon dioxide 100 times faster than current methods.

Research Findings:

Over the years, we've looked at a variety of artificial leaf systems that use sunlight to convert water into liquid fuels and power. Engineers from the University of Illinois Chicago (UIC) provided an interesting example in 2019.

It had a one-of-a-kind design, according to the designers, that made it acceptable for real-world use, as opposed to other laboratory systems that could only function with carbon dioxide from pressurized tanks.

A conventional artificial photosynthesis unit was encased in a transparent capsule filled with water and had a semi-permeable outer layer, according to the solution. When the device was exposed to sunlight, the water evaporated through the pores in the outer layer, and carbon dioxide was sucked in to replace it, where it was converted to carbon monoxide by the unit inside. This CO may then be trapped and converted into synthetic fuels.

The scientists have improved the performance of the device by making a few critical design changes. The team employed low-cost materials to create an electrically charged membrane with both a dry and wet side that works as a water gradient. On the dry side, an organic solvent binds to the carbon dioxide collected and converts it to concentrated bicarbonate, which accumulates on the membrane.

The bicarbonate is then drawn across the membrane and into the watery solution by a positively charged electrode on the wet side, where it is transformed back into carbon dioxide for use in fuels or other applications.

"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 Meenesh Singh, assistant professor of chemical engineering in the UIC College of Engineering and the paper's corresponding author.

Singh added, "It's really intriguing that this real-world use of an electrodialysis-driven artificial leaf had a high flux with a small, modular surface area." "This means it can be stacked, the modules may be added or subtracted to better match the requirement, and it can be utilized economically in homes and classrooms, not just among profitable industrial firms." Four industrial electrodialysis stacks can capture more than 300 kg of CO2 per hour from flue gas, and a small module the size of a household humidifier may remove more than 1 kg of CO2 every day."

(Source: University of Illinois)