Moisture-Powered Materials Could Make Cleaning CO₂ From Air More Efficient

Researchers take step toward improving technologies that pull carbon dioxide directly from the air

Over the past century, the amount of carbon dioxide in Earth's atmosphere has increased dramatically, causing shifting weather patterns and more frequent droughts.

A research team led by Arizona State University Professor Petra Fromme has taken an important step toward lowering the amount of carbon dioxide in the air in an effort to protect ecosystems and reduce future damage to the planet.

In a new study, the team closely examined two promising materials that can capture CO₂ using changes in humidity, a low‑energy process known as moisture-driven direct air capture.

Direct air capture, together with permanent storage, is a promising carbon reduction method that captures carbon dioxide directly from the air.

“This work is so important as it shows for the first time the structural characterization of two direct air capture materials with a unique combination of techniques — ranging from X-ray diffraction to electron microscopy and atomic force microscopy — which we combined with functional studies on the moisture swing mechanisms of carbon dioxide binding and release,” said Fromme, the Paul V. Galvin Professor in ASU's School of Molecular Sciences and director of the Biodesign Institute’s Center for Applied Structural Discovery.

"Our research addresses the urgent challenge of removing carbon dioxide from the atmosphere by investigating materials for low-energy, moisture-driven direct air capture,” says Gayathri Yogaganeshan, Fromme’s doctoral student and first author on the paper published in Materials Today Chemistry.

The study looked at two commercially available polymers (Fumasep FAA-3 and IRA-900) to see how well they work for moisture-driven direct air capture. The goal was to understand how the structure of these materials affects how they adsorb and release carbon dioxide.

Researchers used several imaging and X-ray techniques to examine the materials’ structures at different scales. They also ran experiments that measured how much carbon dioxide and water the materials adsorbed and released under different humidity levels.

The results showed that both materials behave similarly when adsorbing and releasing water, suggesting that water movement is controlled mainly by their molecular structure. However, their ability to capture carbon dioxide differed. The material with larger pores (IRA-900) captured more carbon dioxide and did so more quickly. Additional imaging revealed features like pores, clustering and swelling that help explain these differences.

Overall, the study provides insight into how these materials work during carbon dioxide capture and highlights the important role of moisture.

"These insights provide a foundation for designing more energy-efficient materials for scalable carbon dioxide removal, with implications for advancing practical carbon capture technologies," Yogaganeshan said.

The ASU Core Research Facilities’ Eyring Materials Center supported this research by providing access to state-of-the-art equipment and extensive staff expertise to implement the imaging and X-ray techniques used to examine the materials’ structures at different scales.