Global warming fighter: Cheap nanomaterials from US can speed up carbon capture

With atmospheric CO₂ now at 427 ppm – a 50% rise since the Industrial Revolution – and expected to keep climbing, researchers see the method as key to climate efforts. Yet, its scalability has been hindered by the reliance on costly engineered polymers known as ion exchange resins.

To tackle the issue, the team discovered that inexpensive and sustainable materials – often derived from organic waste or feedstock – can not only make DAC technologies more affordable but also reduce their energy uptake.

Exploring the findings

John Hegarty, a Northwestern materials science and engineering PhD candidate and study co-author, sheds light on the novel nanomaterials including activated carbon, nanostructured graphite, carbon nanotubes, and flake graphite, and metal oxide nanoparticles, including iron, aluminum, and manganese oxides.

“For the first time, we applied a structured experimental framework to identify the significant potential of different materials for CO₂ capture,” Hegarty says. “Of these materials, the aluminum oxide and activated carbon had the fastest kinetics, while the iron oxide and nanostructured graphite could capture the most CO₂.”

The researcher also highlights the importance of a certain material’s pore size – tiny spaces where CO₂ can settle – in determining its carbon capture ability.

Unlike outdated traditional methods, the team believes these more accessible and lower-cost DAC technologies could help offset emissions from areas that are nearly impossible to decarbonize using renewable energy alone, such as agriculture, aviation, and concrete and steel manufacturing.

“The moisture-swing methodology allows for CO₂ to be sequestered at low humidity and released at high humidity, reducing or eliminating the energy costs associated with heating a sorbent material so it can be reused,” McCormick School of Engineering PhD graduate Benjamin Shindel says.

Shindel and the research team say the approach is particularly promising because it allows for carbon removal in a wide range of settings and could be integrated with emerging systems designed to repurpose captured CO₂, marking a step toward a broader carbon reuse economy

Subsequent research

“If you design your system correctly, you can rely on natural gradients, for example, through a day-night cycle or through leveraging two volumes of air of which one is humid, and one is already dry in geographies where that makes sense,” Vinayak P. Dravid, PhD, materials engineering professor at Northwestern University and research leader, says.

After analyzing why ion exchange resins were effective – optimal pore size and surface charge – the team identified more abundant, eco-friendly materials with similar properties.

By systematically analyzing each material, the researchers identified an optimal pore size range, around 50 to 150 angstroms, with the highest swing capacity, revealing a clear link between internal surface area and carbon capture performance.

They now aim to deepen their understanding of the new materials’ life cycles, including overall cost and energy use, and hope their findings will inspire other researchers to think beyond conventional approaches.

“Carbon capture is still in its nascent stages as a field,” Shindel concludes in a press release. “The technology is only going to get cheaper and more efficient until it becomes a viable method for meeting emissions reductions goals for the globe. We’d like to see these materials tested at scale in pilot studies.”

The study has been published in the journal Environmental Science & Technology.