Most direct air capture systems have an energy problem. They need heat — often a lot of it — to release captured CO₂ from their sorbents. That heat costs money and energy, and it’s a major reason DAC still runs $400-1,000+ per tonne.
Moisture-swing sorbents work differently. They absorb CO₂ when dry and release it when wet. No heat required. Just water. It’s an idea that’s been around for over a decade, pioneered by Klaus Lackner at Arizona State University. But making it work efficiently requires understanding exactly what happens inside these materials at a structural level.
A new study from ASU, published in Materials Today Chemistry, just delivered that understanding.
What They Found
Petra Fromme’s team at ASU’s School of Molecular Sciences performed the first comprehensive structural characterization of two commercially available moisture-swing polymers: Fumasep FAA-3 and IRA-900.
Using a battery of techniques — X-ray diffraction, electron microscopy, atomic force microscopy — combined with functional measurements of CO₂ and water sorption, they mapped how these materials behave at different scales and humidity levels.
The key finding: both polymers handle water similarly (suggesting molecular structure controls water movement), but their CO₂ capture performance diverges sharply. IRA-900, the material with larger macropores, captured more CO₂ and captured it faster.
In other words: macropore structure governs CO₂ sorption capacity and kinetics. Bigger pores mean faster, more efficient carbon capture.
Why This Matters
This might sound like a niche materials science result, but it has direct implications for the future cost of DAC.
Right now, the dominant DAC companies (Climeworks, Carbon Engineering/Oxy, Heirloom) use temperature-swing or chemical processes that require significant energy input. Moisture-swing systems could dramatically cut that energy bill — but only if the sorbent materials can be optimized for capacity and speed.
Fromme’s team just identified the structural variable that matters most. That turns sorbent development from trial-and-error into targeted engineering. You want better DAC performance? Design materials with optimal macropore architecture.
“This work is so important because it shows for the first time the structural characterization of two direct air capture materials with a unique combination of techniques,” Fromme said.
The Broader DAC Materials Race
Cheaper DAC probably won’t come from building bigger versions of today’s plants. It’ll come from fundamentally different sorbent materials that capture CO₂ more efficiently, with less energy, and at lower cost to manufacture.
This study is a step in that direction. By revealing the structural characteristics that control performance, it gives materials scientists a roadmap for designing next-generation moisture-swing sorbents optimized from the atomic level up.
The lead author, doctoral student Gayathri Yogaganeshan, put it simply: “Our research addresses the urgent challenge of removing carbon dioxide from the atmosphere by studying materials for low-energy, humidity-activated direct air capture.”
Low-energy DAC at scale would change the economics of carbon removal entirely. We’re not there yet — but now we know what to optimize.
Sources: Nanowerk, Yogaganeshan et al., Materials Today Chemistry (DOI: 10.1016/j.mtchem.2026.103465), Enerzine