The first low-cost system for splitting carbon dioxide

June 5, 2017
Ball-and-stick model of carbon dioxide. Credit: Wikipedia

Using Earth-abundant materials, EPFL scientists have built the first low-cost system for splitting CO2 into CO, a reaction necessary for turning renewable energy into fuel.

The future of clean energy depends on our ability to efficiently store energy from renewable sources and use it later. A popular way to do this is to electrolyze carbon dioxide to carbon monoxide, which is then mixed with hydrogen to produce liquid hydrocarbons like gasoline or kerosene that can be used as fuel. However, we currently lack efficient and Earth-abundant catalysts for the initial splitting of CO2 into CO and oxygen, which makes the move into expensive and prohibitive. EPFL scientists have now developed an Earth-abundant catalyst based on copper-oxide nanowires modified with . The system can split CO2 with an efficiency of 13.4%. The work is published in Nature Energy, and can help worldwide efforts to synthetically produce carbon-based fuels from CO2 and water.

The research was carried out by the lab of Michael Grätzel at EPFL. Grätzel is known worldwide for the invention of the first ever (or "Grätzel cells"). The catalyst, developed by PhD student Marcel Schreier and postdoc Jingshan Luo, is made by depositing an atomic layer of tin oxide on copper oxide nanowires. By using such Earth-abundant materials, the design keeps the cost of the catalyst low while significantly increasing the yield of CO, as opposed to the other products that are generated from CO2 electrocatalysis.

The catalyst was integrated into a CO2 electrolysis system and linked to a triple-junction solar cell (GaInP/GaInAs/Ge) to make a CO2 electrolyzer. The system uses the catalyst as a bifunctional electrode that both reduces CO2 into CO and produces oxygen through what is known as the "oxygen evolution" reaction. The two products are separated with a bipolar membrane.

Using solar , the system was able to selectively convert CO2 to CO with an efficiency of 13.4%, and do so with a Faradaic efficiency up to 90%—this describes how efficiently electrical charge is transferred in a electrocatalysis system like the one developed here. "The work sets a new benchmark for solar-driven CO2 reduction," says Luo.

"This is the first time that such a bi-functional and low-cost is demonstrated," adds Schreier. "Very few catalysts—except expensive ones, like gold and silver—can selectively transform CO2 to CO in water, which is crucial for industrial applications."

Explore further: Researchers report new, more efficient catalyst for water splitting

More information: Marcel Schreier, Florent Héroguel, Ludmilla Steier, Shahzada Ahmad, Jeremy S. Luterbacher, Matthew T. Mayer, Jingshan Luo, Michael Grätzel. Solar conversion of CO2 to CO using Earth-abundant electrocatalysts prepared by atomic layer modification of CuO. Nature Energy 2, 17087 (05 June 2017). nature.com/articles/doi:10.1038/nenergy.2017.87

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11 comments

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Hyperfuzzy
1 / 5 (5) Jun 05, 2017
Would this not create another uncontrollable environmental loop. If you are gonna control nature the CO2 has to re-enter the food chain, naturally; so, first define the problem holistically. The oceans are dying. Your focus upon the causal object and its destruction over 100 years, over the entire planet. Anyway, nice work. Can we simply enhance "Green". I don't know. Throwing gasoline on the fire?
BackBurner
1 / 5 (5) Jun 05, 2017
Lovely. An invention that has the ability to economically convert a non-toxic gas to a toxic gas. Be still my heart.

Here's an idea? Get rid of the catalytic converters that change CO into CO2 at the tailpipe. Cut out the middleman.
Da Schneib
4 / 5 (1) Jun 05, 2017
Excellent- this transforms CO₂ into fuel. We can take the CO₂ out of the atmosphere and out of the ocean. In addition, it offsets fossil fuels, for a double bonus.

Now let's see how quickly they can get this catalyst into production.
FredJose
1 / 5 (3) Jun 05, 2017
Perhaps the writers of the article could have gone just a little farther and explained the next step in energy production. Right now it's not clear to the lay person how Carbon Monoxide and water is such a wonderful combination. As far as most are concerned - as seen by BackBurner - this raises a question of what to do with the poisonous gas? A very valid question in the absence of any further explanation.
manfredparticleboard
5 / 5 (3) Jun 05, 2017
CO and water is essentially taking fossil fuels out of chemical industry's feed stock. They are the LEGO bricks that can make just about anything. The trouble with CO2 is that it's entropy is so wound down that it's difficult to get anything to react with it, like splitting water, breaking it with high efficiency means you get to use the chemical energy stored in the molecules with little wastage. Cheap electrolysis of water is one half of the holy grail of industry, cheap syngas, the mixture of CO and H2O is the other.
RealScience
5 / 5 (3) Jun 05, 2017
... explained the next step in energy production...


It could have been emphasized more, but it is in the article:
A popular way to do this is to electrolyze carbon dioxide to carbon monoxide, which is then mixed with hydrogen to produce liquid hydrocarbons like gasoline or kerosene that can be used as fuel.


This article is only on the CO2-splitting part. Other parts are getting hydrogen (probably from splitting water, since this is for storing renewable energy), and then combining the carbon monoxide and hydrogen to produce methanol, or, by getting rid of the second oxygen, a hydrocarbon such as methane or even gasoline.

If the 13.4% is total efficiency (including the ~40%-efficient tandem solar cell), then that's getting useful; if it is 13/4% of the electricity then they have a long way to go.
Dingbone
Jun 05, 2017
This comment has been removed by a moderator.
RealScience
5 / 5 (5) Jun 05, 2017
... the production of raw sources for renewables consumes more fossil fuels, than they can replace...


While decades ago a solar panel took more energy to make than it produced i its life, the energy used has steadily dropped while that produced has steadily increased, and a typical solar panel now produces more than 10 times as much as was used to make it.

Solar PV is no longer either expensive or a net drain of energy. PV's remaining issue it intermittency - the sun does not always shine when you need power.

And wind has an EROI better than most new oil fields - again the issue is not cost or energy,
but the need for storage.

And storage is what this research is about. Right now the inefficiency of converting CO2 and H2O to fuels to store the energy would be make the resulting fuels far to expensive, but at the rate that the cost of PV is dropping it MIGHT make sense relatively soon, so the research is well worth doing.
BubbaNicholson
2 / 5 (2) Jun 08, 2017
Photosynthesis is less expensive, and will ramp up of its own accord.
Parsec
not rated yet Jun 23, 2017
Would this not create another uncontrollable environmental loop. If you are gonna control nature the CO2 has to re-enter the food chain, naturally; so, first define the problem holistically. The oceans are dying. Your focus upon the causal object and its destruction over 100 years, over the entire planet. Anyway, nice work. Can we simply enhance "Green". I don't know. Throwing gasoline on the fire?


The oceans are drying? Really? You honestly believe that converting CO2 to CO is "controlling nature"? Seriously?

What on earth are you doing on a science news site? Most people completely ignorant of science stay with the sports news or the funnies.
Hyperfuzzy
not rated yet Jun 23, 2017
Would this not create another uncontrollable environmental loop. If you are gonna control nature the CO2 has to re-enter the food chain, naturally; so, first define the problem holistically. The oceans are dying. Your focus upon the causal object and its destruction over 100 years, over the entire planet. Anyway, nice work. Can we simply enhance "Green". I don't know. Throwing gasoline on the fire?


The oceans are drying? Really? You honestly believe that converting CO2 to CO is "controlling nature"? Seriously?

What on earth are you doing on a science news site? Most people completely ignorant of science stay with the sports news or the funnies.

Thanks for the reprimand. But you do not understand nature's sensitivity. This is an invalid argument, sports and funnies. You do know it has no logic.

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