Rocket-inspired reaction yields record surface area of ​​carbon

Researchers at Cornell University have developed a nanoporous carbon with the highest surface area ever reported using a chemical reaction inspired by rocket fuel ignition. This breakthrough technology has already proven beneficial for carbon capture and energy storage technologies.

Scientists are continually working to improve carbon’s porosity. This exposes more of the material’s surface, optimizing its performance in applications such as pollutant adsorption and electrical energy storage.

The new synthesis technique, detailed in the journal ACS Nano, pushes the surface area of ​​carbon to an unprecedented 4,800 square meters per gram, which is equivalent to the size of a football field packed into a teaspoon of the material .

“Increasing the surface area per mass is very important, but you can end up with no material left at all; it’s just air,” said lead author Walter R. Reed, a professor in the Department of Materials Science and Engineering. said one Emmanuel Giannelis. Earned a Ph.D. in Engineering from Cornell. “So the challenge is how much of that porosity can you introduce and still leave the structure and still have enough yield to do something practical.”

To address this challenge, Giannelis turned to postdoctoral researcher Nikolaos Chalmpes. He was designing materials using highly reactive reactions that occur spontaneously when certain chemicals mix and release rapid, powerful bursts of energy.

“I was trying to understand how to harness and control these unexplored reactions to synthesize a variety of carbon nanostructures, and found that by adjusting various parameters it was possible to achieve ultra-high porosity. “We found that there is a difference between the two,” said Chalmpes, lead author of the study. “Until then, these reactions were only used in rocket and aircraft systems, and deep space probes for propulsion and hydraulic power.”

The technology starts with sucrose and a template material that helps shape the carbon into a structured shape. When mixed with certain chemicals, hypergolic reactions ignite, resulting in carbon tubes containing a high concentration of reactive molecular rings made up of five carbon atoms, rather than the typical six-membered rings found in most carbon structures. is formed.

In the final step, the material is treated with potassium hydroxide to etch away unstable structures and create an intricate network of microscopic pores.

“When you do this very fast reaction, you create the perfect situation where the system cannot normally relax and go into its lowest energy state,” Gianneris said. “The speed of hypergolic reactions allows us to capture metastable states of matter that cannot be obtained with the slow heating of normal reactions.”

Researchers and collaborators at Cornell University and Greece’s Democritos National Center for Scientific Research have found that the nanoporous material can adsorb carbon dioxide with nearly twice the capacity of traditional activated carbon, increasing the total capacity to 99% in just two uses. We demonstrated that it is possible to capture %. It is one of the fastest acting adsorbents of its kind.

The new material also shows promise in energy storage, achieving a volumetric energy density of 60 watt-hours per liter, four times higher than commercially available activated carbon.

“This approach provides an alternative strategy for designing and synthesizing carbon-based materials suitable for adsorbents, catalyst supports, and supercapacitor active materials, especially in applications requiring space efficiency.” said Chalmpes, who also uses the technique to create nanoparticle alloys.

“Furthermore, the unique experimental conditions of hypergolic reactions provide an alternative route for the design and synthesis of electrocatalysts with enhanced properties.”