Artificial leaves, similar in function to naturally occurring leaves, use photosynthesis to transform carbon dioxide into other chemical compounds. While the leaves found in nature transform water and carbon dioxide into their desired fuel source—carbohydrates—artificial leaves can be used to distill fuel precursors like carbon monoxide.
However, a problem exists for artificial leaves. They work efficiently only under strict lab conditions, and those conditions aren’t found in the ambient environment.
“So far, all designs for artificial leaves that have been tested in the lab use carbon dioxide from pressurized tanks. In order to implement successfully in the real world, these devices need to be able to draw carbon dioxide from much more dilute sources, such as air and flue gas, which is the gas given off by coal-burning power plants,” said Meenesh Singh, assistant professor of chemical engineering in the UIC College of Engineering.
To improve the efficiency of their artificial leaves and make them capable of performing in the real world, UIC engineers created a novel solution.
Singh and graduate student Aditya Prajapati encapsulated a previously engineered artificial leaf inside a transparent, semipermeable membrane filled with ammonium resin and water. When heated by sunlight, the new artificial leaf construct can evaporate water through its semipermeable body, making it possible to selectively capture carbon dioxide from the exterior environment. With carbon dioxide stored within its membrane, the artificial leaf can begin its “photosynthetic” process that transforms carbon dioxide into carbon monoxide.
According to UIC engineers, 360 of their leaves, each 1.7 meters long and 0.2 meters wide, could produce a half ton of carbon monoxide per day. That carbon monoxide could be used as the basis of a synthetic fuel. Additionally, engineers project that if a 500-meter square area were to be covered with their artificial leaves, 10 percent of the ambient carbon dioxide within a distance of 100 metersfrom the array could be scrubbed from the atmosphere in a day and transformed into useful fuel.