Anti-climate change tech: DNA tethers catalyst to cheap carbon electrode

The greenhouse gas carbon dioxide (CO₂) can be converted to carbon monoxide (CO). CO is a starting material that can be used to make all kinds of things ranging from fuels to plastics to specialty chemicals, e.g., titanium dioxide (in white paint), ethanol, methanol, acetic anhydride, formic acid, methyl formate, N,N-dimethylformamide, propanoic acid, and phosgene (a lethal nerve gas, but used to make other higher value compounds). All of those are major commodities in commerce. If an energy efficient way to convert CO₂ to CO could be found, the idea of huge scale carbon capture goes from economically impossible concept to a possibly plausible (profit-generating) economic reality. Maybe.

Boffins at MIT have found a method to use electricity to CO₂ to CO at a claimed 100% efficiency (that sounds impossible, but let's ignore that):

CO₂ on the right is 

converted to CO on the left 

If scaled up for industrial use, this process could help to remove carbon dioxide from power plants and other sources, reducing the amount of greenhouse gases that are released into the atmosphere.

“This would allow you to take carbon dioxide from emissions or dissolved in the ocean, and convert it into profitable chemicals. It’s really a path forward for decarbonization because we can take CO₂, which is a greenhouse gas, and turn it into things that are useful for chemical manufacture,” says Ariel Furst, the Paul M. Cook Career Development Assistant Professor of Chemical Engineering and the senior author of the study.

The new approach uses electricity to perform the chemical conversion, with help from a catalyst that is tethered to the electrode surface by strands of DNA. This DNA acts like Velcro to keep all the reaction components in close proximity, making the reaction much more efficient than if all the components were floating in solution.

Furst has started a company called Helix Carbon to further develop the technology. Former MIT postdoc Gang Fan is the lead author of the paper, which appears in the Journal of the American Chemical Society Au. 

Converting carbon dioxide into useful products requires first turning it into carbon monoxide. One way to do this is with electricity, but the amount of energy required for that type of electrocatalysis is prohibitively expensive.

To try to bring down those costs, researchers have tried using electrocatalysts, which can speed up the reaction and reduce the amount of energy that needs to be added to the system. One type of catalyst used for this reaction is a class of molecules known as porphyrins, which contain metals such as iron or cobalt and are similar in structure to the heme molecules that carry oxygen in blood.

To attach 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 can be snapped together, forming a permanent bond. A complementary DNA sequence is then attached to the porphyrin catalyst, so that when the catalyst is added to the solution, it will bind reversibly to the DNA that’s already attached to the electrode — just like Velcro.

Using this approach, the researchers were able to boost the Faradaic efficiency of the reaction to 100 percent, meaning that all of the electrical energy that goes into the system goes directly into the chemical reactions, with no energy wasted. When the catalysts are not tethered by DNA, the Faradaic efficiency is only about 40 percent.

This technology could be scaled up for industrial use fairly easily, Furst says, because the carbon electrodes the researchers used are much less expensive than conventional metal electrodes. The catalysts are also inexpensive, as they don’t contain any precious metals, and only a small concentration of the catalyst is needed on the electrode surface.

The point here is that lots of researchers are working on finding a way to make carbon capture economically profitable. The reason for that is that humans cannot get their s**t together to seriously deal with global warming. That is especially true in the US where America's powerful, corrupt radical right extremist authoritarians still say (but not necessarily believe) that global warming is a hoax, not serious or otherwise something to be denied, downplayed, ignored and/or otherwise rationalized into near or complete non-existence.

This approach is surprising to me because it relied on biomolecules or biology-inspired molecules (DNA and prophyrins) for use in a proposed huge scale industrial process. Normally, biomolecules are too fragile to withstand typical industrial high temperature conditions. Presumably this process operates at relatively low temperatures, i.e., less that water's boiling point, which is below the melting (separation) point of the DNA strands in the double helix.

Porphyrins chemical structure

By Germaine: Global warming believer 

Earth is vexed