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Scalable graphene membranes could supercharge carbon capture

Capturing carbon dioxide (CO₂) from industrial emissions is crucial in the fight against climate change. But current methods, like chemical absorption, are expensive and energy-intensive. Scientists have long eyed graphene—an atom-thin, ultra-strong material—as a promising alternative for gas separation, but making large-area, efficient graphene membranes has been a challenge.

Now, a team at EPFL, led by Professor Kumar Agrawal, has developed a scalable technique to create porous graphene membranes that selectively filter CO₂ from gas mixtures. Their approach slashes production costs while improving membrane quality and performance, paving the way for real-world applications in carbon capture and beyond.

The study has been in Nature Chemical Engineering.

Graphene membranes are excellent at separating gases because they can be engineered with pores just the right size to let CO₂ through while blocking larger molecules like nitrogen. This makes them ideal for capturing CO₂ emissions from power plants and industrial processes. But there's a catch: manufacturing these membranes at a meaningful scale has been difficult and costly.

Most existing methods rely on expensive copper foils to grow high-quality graphene needed for membranes and require delicate handling techniques that often introduce cracks, reducing membrane efficiency. The challenge has been to find a way to create large, high-quality graphene membranes in a cost-effective, reproducible manner.

The EPFL team tackled these challenges head-on. First, they developed a method to grow high-quality graphene on low-cost copper foils, dramatically cutting down material expenses. Then, they refined a chemical process using ozone (O₃) to etch tiny pores into the graphene, allowing for highly selective CO₂ filtration.

Crucially, they improved how the gas interacts with the graphene, ensuring uniform pore formation over large areas—a key step toward industrial scalability.

To solve the issue of membrane fragility, the researchers also introduced a novel transfer technique. Instead of floating the delicate graphene film onto a support, which often leads to cracks, they designed a direct transfer process inside the membrane module that eliminates handling issues and reduces failure rates to near zero.

Using their new approach, the researchers successfully created 50 cm² graphene membranes—far larger than what was previously feasible—with near-perfect integrity. The membranes demonstrated exceptional CO₂ selectivity and high gas permeance, meaning they efficiently let CO₂ through while blocking unwanted gases.

Moreover, by optimizing the oxidation process, they were able to increase the density of CO₂-selective pores, further enhancing performance. Computational simulations confirmed that improving gas flow across the membrane played a crucial role in achieving these results.

This breakthrough could change the game for carbon capture. Traditional CO₂ capture technologies rely on energy-intensive chemical processes, making them complex and expensive for widespread use. Graphene membranes, on the other hand, require no heat input, and operate using simple pressure-driven filtration, significantly reducing energy consumption.

Beyond carbon capture, this method could be applied to other gas separation needs, including hydrogen purification and oxygen production. With its scalable production process and cost-effective materials, EPFL's innovation brings graphene membranes one step closer to commercial viability.