Illinois and Toyota engineers build a battery-like direct air capture device that pulls CO2 from the air

Engineers at the University of Illinois Urbana-Champaign, working with the Toyota Research Institute of North America, have built a battery-like direct air capture device that removes carbon dioxide from the atmosphere using electricity and saltwater chemistry instead of heat. The results, published July 9, 2026, by mechanical science and engineering professor Kyle Smith, Illinois graduate students Paul Rozzi and JeongA Lee, and Toyota researchers Chip Roberts and Tim Arthur, appear in the journal “Environmental Science and Technology” under the title “Toward a Low-Energy Direct-Air Capture Cycle by Reversible Proton-Intercalation-Mediated Alkalization.”

Most existing carbon-capture technology targets point sources such as power-plant smokestacks, where CO2 concentrations are high. “Point source methods are important, but they don’t deal with the vast amount of CO2 already mixed into the air at much lower concentrations,” Smith said in the university’s announcement. “Our work is aimed at that legacy problem.”

How the battery-like direct air capture device works

The device uses an electrochemical cell built around potassium-stabilized, proton-intercalation manganese dioxide electrodes to swing the pH of a saltwater solution. In one step, an applied electric field makes the solution more alkaline, which lets it absorb CO2 from the surrounding air. In a second step, the solution is made less alkaline again, causing the captured CO2 to bubble back out in a purified form that can be stored or reused. “What’s innovative about our work is that we use proton-intercalation electrodes in what we call a cation-compensated cell,” Smith said. “That design lets us operate in an alkaline range where CO2 is much more soluble, which is crucial for making direct air capture practical.”

The team treated the process as a thermodynamic cycle, similar to the cycles engineers use to design power plants, but mapped in terms of dissolved inorganic carbon and potassium ion concentration rather than pressure and volume. “By framing our process as a thermodynamic cycle in this particular space, we could see where energy was being wasted and how to redesign the cycle,” Lee said.

Source: University of Illinois Urbana-Champaign News Bureau, July 9, 2026.

Still a laboratory-stage technology

The researchers said the approach is promising but not yet ready for large-scale deployment. The device relies on two liquid streams that ideally stay separate, but in practice some mixing occurs when flows are switched, cutting into efficiency. “Inter-stream mixing is one of the biggest issues we’re dealing with now,” Rozzi said. “If we can limit that mixing or design around it, we can significantly improve both energy consumption and productivity.” The Illinois announcement does not report a measured capture cost or energy-per-mole figure for the device, so those remain open questions the team’s continuing work will need to address.

For Toyota, the work is part of a broader research effort. “Our work with Professor Smith and the U. of I. team on electrochemical direct air capture provides useful insights into how materials, electrochemistry and process design can be combined to address challenging CO2 separation problems,” said Chip Roberts of the Toyota Research Institute of North America. “This type of early-stage research supports Toyota’s broader effort to explore innovative pathways toward long-term decarbonization.” The project builds on a wider push to pair engineering innovation with lower resource use, an approach Winss Solutions has examined in how innovation and sustainability work together for a better future, and it adds an electrochemical route alongside other capture methods such as Orca’s large-scale direct air capture plant.

Background on direct air capture research

Direct air capture targets the CO2 already dispersed through the atmosphere at low concentrations, a harder separation problem than capturing concentrated CO2 at a smokestack, and one climate scientists say will be needed alongside emissions cuts to meet global climate targets. Most current direct air capture systems rely on heat to drive the chemical reactions that absorb and release CO2, which makes energy use one of the technology’s central cost drivers. The Illinois-Toyota device is among a growing set of electrochemical alternatives that substitute electricity for heat, an approach researchers say could in principle be run on renewable power and sited more flexibly than heat-driven systems. The work was supported by Toyota Motor North America and the University of Illinois’ Campus Research Board through an Arnold O. Beckman Award, and two related patent applications have been filed, with further engineering needed before the cycle could be scaled beyond the laboratory.

Sources: University of Illinois Urbana-Champaign News Bureau; Environmental Science & Technology

Featured image: photo by Ramesh Kambattan on Pexels (free Pexels license).

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Figen Sekin

I specialize in sustainability education, curriculum co-creation, and early-stage project strategy. At WINSS, I craft articles on sustainability, transformative AI, and related topics. When I’m not writing, you’ll find me chasing the perfect sushi roll, exploring cities around the globe, or unwinding with my dog Puffy — the world’s most loyal sidekick.