MIT chemical engineers have devised an environment friendly technique to convert carbon dioxide to carbon monoxide, a chemical precursor that can be utilized to generate helpful compounds corresponding to ethanol and different fuels.
If scaled up for industrial use, this course of may assist to take away carbon dioxide from energy vegetation and different sources, lowering the quantity of greenhouse gases which are launched into the environment.
“This may assist you to take carbon dioxide from emissions or dissolved within the ocean, and convert it into worthwhile chemical compounds. It’s actually a path ahead for decarbonization as a result of we will take CO2, which is a greenhouse fuel, and switch it into issues which are helpful for chemical manufacture,” says Ariel Furst, the Paul M. Prepare dinner Profession Growth Assistant Professor of Chemical Engineering and the senior writer of the examine.
The brand new strategy makes use of electrical energy to carry out the chemical conversion, with assist from a catalyst that’s tethered to the electrode floor by strands of DNA. This DNA acts like Velcro to maintain all of the response parts in shut proximity, making the response rather more environment friendly than if all of the parts have been floating in resolution.
Furst has began an organization referred to as Helix Carbon to additional develop the expertise. Former MIT postdoc Gang Fan is the lead writer of the paper, which seems within the Journal of the American Chemical Society Au. Different authors embody Nathan Corbin PhD ’21, Minju Chung PhD ’23, former MIT postdocs Thomas Gill and Amruta Karbelkar, and Evan Moore ’23.
Breaking down CO2
Changing carbon dioxide into helpful merchandise requires first turning it into carbon monoxide. A technique to do that is with electrical energy, however the quantity of vitality required for that sort of electrocatalysis is prohibitively costly.
To attempt to convey down these prices, researchers have tried utilizing electrocatalysts, which may velocity up the response and scale back the quantity of vitality that must be added to the system. One sort of catalyst used for this response is a category of molecules often known as porphyrins, which comprise metals corresponding to iron or cobalt and are comparable in construction to the heme molecules that carry oxygen in blood.
Throughout such a electrochemical response, carbon dioxide is dissolved in water inside an electrochemical machine, which comprises an electrode that drives the response. The catalysts are additionally suspended within the resolution. Nonetheless, this setup isn’t very environment friendly as a result of the carbon dioxide and the catalysts have to encounter one another on the electrode floor, which doesn’t occur fairly often.
To make the response happen extra ceaselessly, which might increase the effectivity of the electrochemical conversion, Furst started engaged on methods to connect the catalysts to the floor of the electrode. DNA gave the impression to be the perfect alternative for this utility.
“DNA is comparatively cheap, you’ll be able to modify it chemically, and you may management the interplay between two strands by altering the sequences,” she says. “It’s like a sequence-specific Velcro that has very sturdy however reversible interactions you could management.”
To connect single strands of DNA to a carbon electrode, the researchers used two “chemical handles,” one on the DNA and one on the electrode. These handles may be snapped collectively, forming a everlasting bond. A complementary DNA sequence is then hooked up to the porphyrin catalyst, in order that when the catalyst is added to the answer, it’ll bind reversibly to the DNA that’s already hooked up to the electrode — similar to Velcro.
As soon as this technique is ready up, the researchers apply a possible (or bias) to the electrode, and the catalyst makes use of this vitality to transform carbon dioxide within the resolution into carbon monoxide. The response additionally generates a small quantity of hydrogen fuel, from the water. After the catalysts put on out, they are often launched from the floor by heating the system to interrupt the reversible bonds between the 2 DNA strands, and changed with new ones.
An environment friendly response
Utilizing this strategy, the researchers have been in a position to increase the Faradaic effectivity of the response to 100%, which means that all the electrical vitality that goes into the system goes straight into the chemical reactions, with no vitality wasted. When the catalysts usually are not tethered by DNA, the Faradaic effectivity is barely about 40 p.c.
This expertise could possibly be scaled up for industrial use pretty simply, Furst says, as a result of the carbon electrodes the researchers used are a lot cheaper than typical steel electrodes. The catalysts are additionally cheap, as they don’t comprise any treasured metals, and solely a small focus of the catalyst is required on the electrode floor.
By swapping in several catalysts, the researchers plan to strive making different merchandise corresponding to methanol and ethanol utilizing this strategy. Helix Carbon, the corporate began by Furst, can also be engaged on additional growing the expertise for potential business use.
The analysis was funded by the U.S. Military Analysis Workplace, the CIFAR Azrieli World Students Program, the MIT Vitality Initiative, and the MIT Deshpande Middle.