These Gold ‘Nanoneedles’ Could Be a Powerful Weapon Against Climate Change
They function like lightning rods, catalyzing a reaction that splits CO2 apart.
Gold nanoneedle lightning rods concentrate CO2 for reaction. Image: Phil De Luna/U of T Engineering
For such a tiny molecule, carbon dioxide has a big impact. CO2 is, of course, the main byproduct of burning fossil fuels and is an excellent greenhouse gas, so we have to figure out how to curb our emissions. 2015 was the hottest year in history, with 2016 easily on track to beat it.
Scientists are chomping at the bit to find a way to capture this gas and turn it into something less environmentally damaging, a process called carbon capture and storage. The answer could be newly engineered tiny golden "nanoneedles," which function like a lightning rod to catalyze a reaction that splits CO2 molecules apart.
The research group of Ted Sargent, a professor in the department of electrical and computer engineering at the University of Toronto, along with their collaborators have developed a prototype for a catalyst that can wrench an oxygen atom from the doublet in a CO2 molecule, producing carbon monoxide—a great building block for other types of fuel, including ethanol and diesel, and a first step in sequestering that pesky carbon so that it doesn't make its way into the atmosphere and dial up the temperature even further.
Using catalytic processes to try to break apart carbon dioxide into its constituent parts is not a new idea. But the process has been dogged by technical limitations. Large quantities of dissolved salts are typically used, but this method is cumbersome. Carbon dioxide also tends not to be absorbed very well into the materials that make up catalysts, meaning the reaction can proceed at a snail's pace.
Sargent's breakthrough, like many in materials science these days, has to do with manufacturing a nifty structure on the nano-scale, leapfrogging these limitations. As described in a paper out Wednesday in the journal Nature, the group has managed to fabricate tiny needles made of gold. These nanoneedles, as his lab has dubbed them, have incredibly fine points—some 10,000 times thinner than a human hair.
The action happens when an electrical charge is applied across the length of the tiny gold needles. "The catalyst is about a nanometre in size and has a very high curvature," Phil De Luna, a doctoral student in Sargent's lab and one of the lead scientists on the project, told me in an interview. "These nanoneedles—at the very tips—have a very high local electric field. It's like a lightning rod."
This intense field lures carbon dioxide molecules to the tips of the needles, where they stick and stay. Once in place, the CO2 reacts with a potassium ion to produce hydrogen and carbon monoxide. "It's the fastest catalyst to date," said De Luna. "It's 10 times faster than the last known gold catalyst."
De Luna's tech is also very good at its job: 97 per cent of the CO2 put into the system is converted to carbon monoxide. "We're really looking at the atomic level at how this new concept can increase the rate of the reaction," he said.
De Luna envisions industrial versions of the technology built into objects that spew CO2, like car tailpipes and industrial smokestacks. "We're taking the carbon dioxide and turning it into fuel. We're proposing a carbon-neutral approach to long-term [carbon] storage," he said.
Given that the tech uses gold, one of the planet's most durable materials, such ideas may not be so farfetched. The catalytic converter in your car may get a lot more expensive, but if it makes driving carbon neutral, there's sure to be a market for it.
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