Researchers present a megatonne-scale design that converts captured CO2 into graphene nanocarbons, combining carbon removal with production of valuable industrial materials.
(Nanowerk Spotlight) In the design drawings, the potlines stretch for hundreds of meters, each lined with massive electrolysis modules humming under the push of high electric currents. It looks like an aluminium smelter, but instead of producing metal, every unit is pulling carbon dioxide out of industrial exhaust and rebuilding it as fine nanocarbon powders.
At full capacity, the facility would process a million tonnes of CO₂ each year, locking the carbon away in materials strong enough for aerospace composites, conductive enough for electronics, and stable enough to last centuries.
(Top: operational aluminium smelting potline. Bottom: analogous Genesis Device layout using modular electrolysis units to reach one megatonne per year CO₂-to-nanocarbon conversion, adopting the same scalable, multi-line configuration proven in heavy industry. (Image: Reprinted from DOI:10.3390/cryst15080680, CC BY) (click on image to enlarge)
“Following the blueprint of aluminium smelting, these modules can be linked into potlines, each operating continuously to convert waste gas into stable carbon materials,” Prof. Stuart Licht, founder of C2CNT, tells Nanowerk. “Multiple lines could run side by side, building toward megatonne capacity.”
By adjusting factors such as electrolyte chemistry, temperature, current density, and the presence of nucleating metals like iron, nickel, and chromium, the process can produce distinct nanocarbon forms: conventional multiwalled carbon nanotubes (CNTs), magnetic CNTs with embedded ferromagnetic particles, helical CNTs, carbon nano-scaffolds, and carbon nano-onions (CNOs).
The research shows that morphology control—long established in the lab—remains consistent in industrial-scale electrolysers, and that lower-cost electrolytes without lithium can be used without compromising quality.
Diversifying the product range has been central to the team’s strategy. Magnetic CNTs can be recovered from composites using magnets, aiding recycling. Helical CNTs and nano-scaffolds have unique structural properties valuable in catalysis and electronics. CNOs, concentric graphene shells just tens of nanometres across, have emerged as a potential replacement for carbon black and synthetic graphite—materials whose conventional production releases tens of millions of tonnes of CO₂ each year.
Industrial pilot plant carbon capture by molten carbonate electrolytic splitting of CO2 with 5% CO2 flue gas from the Shepard Natural Gas Power Plant in Calgary, CA. (A) The Genesis Device® kiln used for large-scale CO2 molten carbonate electrolysis utilizes modules designed to convert 100 t CO2/year. (B1,B2) The cathode upon being lifted from the electrolyte and cooled. (C) Front, side, and back views of 100 t CO2/year Genesis Device® module, including illustrations of the carbon pot and the saw-tooth shaped cathode. The latter maintains cathode edge-growth deposition thickness. (Image: Reprinted from DOI:10.3390/cryst15080680, CC BY) (click on image to enlarge)
The new results show that simply lowering the operating temperature near the electrolyte’s melting point reduces transition metal activity enough to favour CNO growth. The outcome is tightly packed clusters of uniform particles with high thermal stability and conductivity. Their size, structure, and durability position them as drop-in replacements for carbon black in tires, battery electrodes, and industrial pigments—applications that consume millions of tonnes annually.
The team notes that while those systems capture CO₂ effectively, they require additional infrastructure for compression, transport, and storage. C2CNT performs capture, concentration, and conversion in a single step, producing a durable solid carbon material at the point of capture.
The analysis draws operational parallels with aluminium smelting—both rely on high-current molten-phase electrolysis in modular units—but highlights that C2CNT operates at lower temperatures, uses oxygen-evolving anodes, and runs directly on raw CO₂ streams without refinement.
The economic implications are significant. In most capture systems, cost is a barrier because the output is a liability that must be stored indefinitely. In C2CNT, the output is a product with established and emerging markets, from reinforced composites to energy storage devices. The graphene nanocarbons also act as a form of permanent sequestration: once embedded in industrial materials, their carbon remains locked away for decades or centuries.
“Our progress represents a shift from laboratory-scale proofs to designs for full industrial integration,” Licht concludes. “The concept of CO₂ conversion potlines—mirroring the structure of aluminium smelters but turning waste gas into engineered carbon materials—offers a concrete picture of how removal could be embedded in heavy industry. In that vision, the hum of electrolysis cells is not just the sound of production, but of atmospheric carbon being pulled out of circulation and solidified into materials that build the infrastructure of the future.”
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