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Graphene quantum dots can convert CO2 into liquid fuels

Graphene quantum dots can conv...
Rice University researchers have used nitrogen-doped graphene quantum dots to convert carbon dioxide into liquid hydrocarbons like ethylene and ethanol, for use as fuel
Rice University researchers have used nitrogen-doped graphene quantum dots to convert carbon dioxide into liquid hydrocarbons like ethylene and ethanol, for use as fuel
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At this scale, the nitrogen-doped graphene quantum dots stand out as circular patches from the substrate supporting them
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At this scale, the nitrogen-doped graphene quantum dots stand out as circular patches from the substrate supporting them
A single nitrogen-doped graphene quantum dot
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A single nitrogen-doped graphene quantum dot
Nitrogen-doped graphene quantum dots, as seen in this transmission electron microscope image, have been found to perform as well as copper at converting CO2 into fuels
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Nitrogen-doped graphene quantum dots, as seen in this transmission electron microscope image, have been found to perform as well as copper at converting CO2 into fuels
Rice University researchers have used nitrogen-doped graphene quantum dots to convert carbon dioxide into liquid hydrocarbons like ethylene and ethanol, for use as fuel
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Rice University researchers have used nitrogen-doped graphene quantum dots to convert carbon dioxide into liquid hydrocarbons like ethylene and ethanol, for use as fuel
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The wonder-material graphene may have a new trick to add to its resume: converting carbon dioxide into liquid fuels. A team at Rice University has used nitrogen-doped graphene quantum dots (NGQDs) as a catalyst in electrochemical reactions that create ethylene and ethanol, and the stability and efficiency of the material is close to that of common electrocatalysts like copper.

Reducing the amount of carbon dioxide that enters the atmosphere is one weapon in the fight to slow climate change, and plenty of research is looking into how we can capture carbon at the source, using clay, engineered bacteria, metal-organic frameworks or materials like the "Memzyme," and sequester it into rock and concrete. Other studies are focusing on how we can convert that captured carbon into liquid hydrocarbons, which can then be used as fuel.

For that purpose, the Rice researchers found that NGQDs are a surprisingly effective electrocatalyst. The materials are made from sheets of graphene a single atom thick, divided into dots only a few nanometers wide. Comprised entirely of carbon, these graphene dots wouldn't be able to convert CO2 by themselves, so the team added nitrogen atoms to the mix, which trigger chemical reactions in response to an electric current, and carbon dioxide.

"Carbon is typically not a catalyst," says Pulickel Ajayan, leader of the study. "One of our questions is why this doping is so effective. When nitrogen is inserted into the hexagonal graphitic lattice, there are multiple positions it can take. Each of these positions, depending on where nitrogen sits, should have different catalytic activity. So it's been a puzzle, and though people have written a lot of papers in the last five to 10 years on doped and defective carbon being catalytic, the puzzle is not really solved."

How it works may remain a mystery for now, but the results are promising regardless. Several materials have been tested as electrocatalysts, with copper rising as one of the main contenders. But in terms of efficiency, the NQGDs were found to perform to about the same level as copper, reducing the amount of carbon dioxide released by up to 90 percent, and converting 45 percent of that captured into small quantities of ethylene and ethanol, to then be used as fuel. The NGQDs were also found to keep this up over a long stretch of time.

A single nitrogen-doped graphene quantum dot
A single nitrogen-doped graphene quantum dot

"It is surprising because people have tried all different kinds of catalysts," says Ajayan. "And there are only a few real choices such as copper. I think what we found is fundamentally interesting, because it provides an efficient pathway to screen new types of catalysts to convert carbon dioxide to higher-value products."

Lab experiments don't always translate to commercial applications though, and the researchers point out that it could be a while before these NGQDs are put to work in a real-world setting. Current industrial practice is to create fuels using thermal catalysis instead of electrocatalysis, as it scales better.

"For that reason, companies probably won't use it any time soon for large-scale production," says Ajayan. "But electrocatalysis can be easily done in the lab, and we showed it will be useful in the development of new catalysts."

Doing so will be the focus of future research, and the team will begin by raising the amount of nitrogen in the mix, to help increase the amount of fuels produced.

The research was published in the journal Nature Communications.

Source: Rice University

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9 comments
guzmanchinky
Our situation is dire, but I am SO hoping for a tech breakthrough soon that can help reduce CO2 quickly. And then please bring on the quick charging batteries for electric cars!
EcoLogical
Drugs like morphine and benzodiazepines (Alprazolam - Xanax, Lorazepam - Ativan, Diazepam - Valium) have multiple benzene rings (same hexagonal structure to graphene) with one or more Nitrogen atoms that replace the carbon atom in the ring. 'Benzodiazepine' means benzene rings with 2 Nitrogen atoms. Perhaps the pharmaceutical industry could collaborate with energy researchers like the team from Rice University.
Note the similarity of the structures for Diazepam and Morphine: https://en.wikipedia.org/wiki/File:Diazepam_structure.svg https://en.wikipedia.org/wiki/File:Diazepam_ball-and-stick_model.png https://en.wikipedia.org/wiki/File:Morphin_-_Morphine.svg https://en.wikipedia.org/wiki/File:Morphine-from-xtal-3D-balls.png
Kpar
Our situation is not so dire- don't worry, be happy. Global Warming is a natural process, and we should welcome it.
That said, where is the energy input in this system? Anything that can be used as fuel provides energy output- the energy has to come from somewhere. In the case of fossil fuels, that energy is in the form of chemical bonds that are broken when they are combusted with O2, producing an exothermic reaction, and results in a lower energy state with the new, more stable carbon-oxygen bond.
If you are going to put Humpty Dumpty back together again, it takes ENERGY.
Robert in Vancouver
Saskatchewan has created a full scale factory that captures CO2, turns it into a commodity, and sells it to companies that use it for making things. But Canada's Liberal left-wing gov't is going to force Canadians to pay a 'carbon tax' instead of expanding Saskatchewan's factory and exporting the technology.
JeffAWI
This is exciting. Any technology that can economically remove even some portion of the excess CO2 in our environment is welcome.
Kpar, I interpret the following quote from the article:
"so the team added nitrogen atoms to the mix, which trigger chemical reactions in response to an electric current, and carbon dioxide."
to indicate that an electric current is applied to induce the reaction. This is the input energy that you wondered about.
robo, a link to the Saskatchewan technology you mention would be helpful to support your argument.
EcoLogical
Kpar, the article says: "the team added nitrogen atoms to the mix, which trigger chemical reactions in response to an ELECTRIC CURRENT, and carbon dioxide".
ljaques
Interesting experiment. I wonder what type of lab would be required for it to be produced, or if small labs could produce cheap local quantities for use by everyone. If you could set one up in your off-grid cabin and produce fuel or extenders for the bike or car by capturing wood stove exhaust, it will catch on quickly.
P.S: If the CO2 situation is so dire, QUICK, stop exhaling! And start planting mature trees. Saplings take _forever_ to capture all that nasty carbon.
MattII
Whether or not you believe in climate change, this is cool, as if it can be scaled up it will reduce the dependency of middle-east oil.
slarmas
IMHO global warming and higher co2 levels are a great thing for many reasons, but that being said I also would like to see the co2 put to a good use, mainly because if you can make fuel stocks from co2 and water with electrical input it creates three great things. 1. A way to store energy from renewable intermittent sources like solar wind and even waves, and 2. It creates a cycle so we are not just putting co2 into the atmosphere but taking it out making the fuels carbon neutral, and 3. It puts the fuel into a form that is easily transportable to areas that need it. So when the four hundred gigawatt solar farm in he Arizona Desert of the future overproduces it can just create hydrocarbon fuels and export them to areas of the country/world that need them. It also would be good for transportation as even though electric motors are extremely efficient and clean, battery technology is bulky, not energy dense (yet), not long lived (though probably long enough for most automobile applications) and quite costly (and going down). The point is if you give me 20 gallons of diesel gas or ethanol it will always get me further than the same weight and space taken up by batteries at a much lower cost. If the liquid fuel comes from renewable that is a great thing.