These Artificial Leaves Can Absorb 10 Times More CO2 From The Air Than Real Leaves

Plants possess a natural ability to purify the air and produce energy while doing so. The ability is called photosynthesis and it is the process whereby plants use water and carbon dioxide from the air to produce carbohydrates using energy from the sun. Scientists have found a way to make this happen artificially. The thing is, they hadn’t been able to get these artificial leaves to work outside the lab because the lab leaves use pure, pressurized carbon dioxide from tanks, which is different than getting it out of the air.

An artificial, bio-inspired leaf. Carbon dioxide (red and black balls) enter the leaf as water (white and red balls) evaporates from the bottom of the leaf. An artificial photosystem (purple circle at the center of the leaf) made of a light absorber coated with catalysts converts carbon dioxide to carbon monoxide and converts water to oxygen (shown as double red balls) using sunlight.” (Image: Meenesh Singh).

But now, researchers from the University of Illinois at Chicago have proposed a design solution that could change everything. Their idea just might be the leaves’ ticket out of the lab and into the environment. Their findings are reported in the journal ACS Sustainable Chemistry & Engineering .“

Meenesh Singh, assistant professor of chemical engineering in the UIC College of Engineering and corresponding author on the paper, said:

“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.”

The only way that these artificial leaves will be able to collect and concentrate carbon dioxide (a potent greenhouse gas) from the air around us to drive their artificial photosynthetic reactions is if they are unhooked from the pressurized carbon dioxide supply.

Image: Meenesh Singh

Here’s how Singh and his colleague Aditya Prajapati, a graduate student in his lab, propose to solve this problem:

• The traditional artificial leaf is placed inside a water-filled capsule constructed out of a semi-permeable membrane.
• When the sunlight warms the water, it evaporates through the membrane – when that happens it gets the capsule to suck in carbon dioxide (co2).
• The CO2 that’s been sucked in then gets converted into carbon monoxide (CO) and oxygen by the artificial leaf inside the capsule.
• The carbon monoxide (CO) could be siphoned from the device and used to create synthetic fuels ranging from gasoline to methanol;
• And the oxygen could be released back into the environment or collected.

In other words, all they have to do is envelope the artificial leaf technology (that has already been developed and works but only in the lab) within this specialized membrane and the whole unit will be able to function outside, like a natural leaf. Furthermore, according to their research, they believe that an artificial leaf built around their design would be 10 times more efficient at converting CO2 to fuel than natural leaves.

Their calculations reveal that 360 of their artificial leaves, each 1.7 meters long and 0.2 meters wide, would generate about half a ton of CO daily, which can be used as a basis for synthetic fuels. If those leaves were to be spread out over 500 square meters, then they could reduce the CO2 levels in the air within 100 meters of the space by 10 percent in just one day.

Singh concludes:

“Our conceptual design uses readily available materials and technology, that when combined can produce an artificial leaf that is ready to be deployed outside the lab where it can play a significant role in reducing greenhouse gases in the atmosphere.”

ORIGINAL: Intelligent Living

by Andrea D. Steffen
February 22, 2019