Humanity must transition from a digging civilization to a separating civilization by mining the atmosphere for raw materials, according to Susumu Kitagawa, a Kyoto University researcher and winner of the Nobel Prize in chemistry. Speaking at the 10th EuChemS Chemistry Congress in Antwerp, Belgium, Kitagawa outlined a vision for extracting carbon, oxygen, and hydrogen directly from the air using advanced porous materials.
Kitagawa won the 2025 chemistry Nobel prize alongside Omar Yaghi and Richard Robson for developing porous coordination polymers, specifically metal–organic frameworks, or MOFs. Kitagawa’s individual contribution focused on developing stable MOFs and subsequently engineering a third generation of these structures that offer greater flexibility than rigid predecessors.
How Metal-Organic Frameworks Capture Gases from Air
MOFs are synthesized by combining a metal with an organic linker, creating a huge, open, three-dimensional crystalline structure where a metal ion sits at the center of each unit. According to Kitagawa, a single gram of a MOF can feature a surface area equivalent to a football pitch, allowing the material to capture and store gases effectively within its vast network of pores.
“Already people use the nitrogen from the air, for instance in the Haber–Bosch method, but the problem is that the hydrogen comes from underground resources – natural gas and petroleum.”
— Susumu Kitagawa, Kyoto University
While industrial processes routinely capture nitrogen from the atmosphere to produce ammonia for fertilizers, gathering other essential elements still relies heavily on fossil fuels. Kitagawa stated that future applications could involve breaking down collected water vapour into oxygen and hydrogen. This harvested hydrogen could then combine with nitrogen for chemical manufacturing or react with captured carbon dioxide to create synthetic liquid fuels.
Did You Know?
Carbon dioxide makes up just 0.04% of our atmosphere, creating a dilute molecule economy that requires highly selective porous materials to capture gases efficiently without excessive energy costs.
Engineering Soft MOFs for Industrial Gas Separation
Kitagawa’s research group addresses the challenge of dilute gases by developing soft, porous MOFs with varied physical behaviors. Some frameworks function as flexible structures that can double in volume when accommodating guest molecules, suiting them for mechanical actuators. Other frameworks exhibit almost no volume change during gas binding, making them ideal for selective gas separation.
Exhaust gases and ambient air normally contain water vapour that hinders the selective capture of carbon dioxide. To overcome this, Kitagawa’s team engineered the pores of their MOFs to be hydrophobic, enabling selective carbon dioxide capture while actively excluding water.
Gill Reid, a past president of the Royal Society of Chemistry and coordination chemistry researcher at the University of Southampton, described Kitagawa’s concept as an extraordinary vision. Reid noted that hearing Kitagawa trace his scientific journey from initial molecular holes to flexible dynamic structures designed for selective adsorption and release of methane and carbon dioxide was deeply inspiring.
Political Hurdles and the Fifty-Year Horizon
Implementing a global shift toward atmospheric mining faces significant economic and political headwinds. Kitagawa pointed out that governments typically focus on electoral cycles lasting two to three years, whereas mining the invisible gold of the air is costly and requires a 50-year development horizon.
To bridge this gap, Kitagawa emphasizes educating younger generations. By advertising these technological pathways at academic gatherings like the EuChemS Chemistry Congress, researchers hope to secure the long-term scientific commitment required to move industries away from subsurface resource extraction.
Frequently Asked Questions
What are metal-organic frameworks (MOFs)?
MOFs are porous crystalline structures made by linking metal ions with organic molecules, creating vast internal surface areas capable of capturing and storing specific gas molecules.
Why is mining the air difficult?
Gases like carbon dioxide exist in dilute concentrations in the atmosphere, making current capture methods energy-intensive and costly without advanced porous materials.
How do hydrophobic MOFs improve carbon capture?
Hydrophobic MOFs repel water vapour present in exhaust and ambient air, allowing the material to selectively capture target gases like carbon dioxide without interference from moisture.
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