GW Researchers Capture and Recycle CO2 to Create Carbon Nanotubes

By Mike Hower
Planet Forward/GWU

Imagine a material as much as 200 times stronger and five times more flexible than steel, but only a fraction of the weight. Such a material could revolutionize the construction of everything from buildings to aircraft. And — even better — to create this material you can actually help mitigate climate change by taking carbon dioxide out of the atmosphere. 

While this might sound like science fiction, it’s actually already science fact. 

Carbon nanotubes are best described as a tiny pipe with walls made of carbon atoms linked neatly together. Each carbon nanotube is only one nanometer (one billionth of a meter) in diameter, which is 2,000 times smaller than a carbon fiber filament.

Despite the numerous applications for carbon nanotubes, they haven’t yet hit the mainstream due to that fact that they’re difficult and expensive to create. But a team of George Washington University chemists said they have found a way to make them by sucking carbon dioxide right out of the atmosphere.

Published recently in the American Chemical Society’s Nano Letters and presented last month by its authors, the research is part of a mounting body of study that looks for ways to “capture” or “sequester” carbon in the atmosphere by trapping it.

The method makes use of the solar thermal electrochemical process, or STEP, first introduced at George Washington University in 2009. The process efficiently removes carbon from the atmosphere and generates staples such as fuels, metals, bleach and construction materials, at high solar efficiency and without carbon dioxide generation. By using the full spectrum of sunlight, STEP captures more solar energy than the most efficient solar cell or photoelectrochemical processes, the researchers said.

“With STEP, the greenhouse gas carbon dioxide is converted into valuable carbon nanofibers and oxygen, iron ore is converted into iron, water is converted into hydrogen fuel and limestone is converted into lime for cement,” said Stuart Licht, a professor of chemistry at George Washington University who headed up the carbon nanotube research. “The thermal portion of sunlight is used to heat raw materials. This solar heat decreases the energy needed to transform these raw materials into useful products in a high temperature molten bath, which dissolves the raw material.”

In other words, solar cells can capture carbon out of the air, and turn it into valuable carbon nanotubes.

This entire process costs far less than normal manufacturing methods, according to the researchers.

However, the market for carbon nanotubes isn’t quite there yet. But Licht said the current market is in a similar position to the plastics market at the beginning of World War II.

“As costs are reduced and its superior strength, lightweight and conductive properties are utilized in construction, transportation, fashion, energy and electronics, it is poised to expand rapidly,” he said. “It is reasonable to expect a size similar to the current plastics market, and at that level the transformation of carbon dioxide to carbon nanofibers can start to mitigate the climate change consequences of anthropogenic carbon dioxide.”

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