Science

Artificial leaf turns sunlight, CO2 and water into synthetic gas

Artificial leaf turns sunlight...
Cambridge's artificial leaf uses two perovskite light absorbers and a cobalt catalyst to convert sunlight, water and carbon dioxide into syngas
Cambridge's artificial leaf uses two perovskite light absorbers and a cobalt catalyst to convert sunlight, water and carbon dioxide into syngas
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Cambridge's artificial leaf uses two perovskite light absorbers and a cobalt catalyst to convert sunlight, water and carbon dioxide into syngas
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Cambridge's artificial leaf uses two perovskite light absorbers and a cobalt catalyst to convert sunlight, water and carbon dioxide into syngas

The humble leaf is an incredible little machine, converting sunlight and carbon dioxide into energy for a plant. Artificial versions could be useful renewable energy sources, or even used to produce fuels. Now, researchers from the University of Cambridge have developed an artificial leaf that can produce synthetic gas (or syngas) without releasing carbon dioxide.

Syngas is made from hydrogen and carbon monoxide, sometimes with a bit of carbon dioxide thrown in. While it can technically be burned to generate electricity or for gas lighting and heating, it more often acts as an intermediate step in manufacturing products, including plastics, fertilizers, and fuels like diesel. Unfortunately, producing it can release carbon dioxide into the atmosphere.

“You may not have heard of syngas itself but every day, you consume products that were created using it,” says Erwin Reisner, senior author of the study. “Being able to produce it sustainably would be a critical step in closing the global carbon cycle and establishing a sustainable chemical and fuel industry.”

To help with that, the Cambridge team developed a new artificial leaf prototype that can produce syngas through photosynthesis. The new device contains two light absorbers made of perovskite, and a cobalt catalyst. When these are placed in water, one side produces oxygen, while the other reduces carbon dioxide and water into carbon monoxide and hydrogen. Those latter two gases can then be combined into syngas.

The team showed that the technology can still work even in relatively low light, like that on cloudy or rainy days. The perovskite was chosen because it’s good at absorbing light and creating a voltage, which is why it’s showing up in solar panels so much lately. Meanwhile the cobalt in the catalyst is lower cost and more efficient at creating carbon monoxide than other materials.

That said, the conversion efficiencies are still quite low – the new design currently produces hydrogen at an efficiency of 0.06 percent and carbon monoxide at 0.02 percent.

The new device joins a range of artificial leaf designs that are being developed to create a range of useful products, like electricity, drugs, fertilizers, and hydrogen fuel. Ultimately, the team hopes to be able to skip the middleman syngas stage.

“What we’d like to do next, instead of first making syngas and then converting it into liquid fuel, is to make the liquid fuel in one step from carbon dioxide and water,” says Reisner. “There is a major demand for liquid fuels to power heavy transport, shipping and aviation sustainably.”

The research was published in the journal Nature Materials.

Source: University of Cambridge

8 comments
Simon Redford
Unless there is a likelihood of a huge improvement in efficiency, why would you want to do this? With good PV giving 20%+ conversion and hydrogen production by electrolysis in the region of 75%, existing kit can produce hydrogen at 15%+ efficiency. If you want to include CO2, then there are processes to synthesise Methanol from Hydrogen and CO2.
DaveWesely
Yes inefficiently creating fuel from air with sunlight so we can extract a third of the energy from the fuel with ICE technology makes so much sense. And it comes with the added benefit of returning the CO2 to the atmosphere! /snark The goal shouldn't be to create fuel so we can burn it. The goal should be to return the carbon back into solid form from the atmosphere.
guzmanchinky
This is interesting! Someday soon the breakthrough will come, an artificial leaf system that can suck as much CO2 out of the air as we like. As far a fuels go, I think once the 5 minute charging battery is built, the only fuel needed will be for airliners.
Science and Econ
CO2 is one of our most precious worldly assets. CO2 is historically LOW right now; not too high. Scientists know that the CO2 eligible for policy-based reduction (Paris' etc. etc.) (banning many modern lifestyle CHOICES and pets) is roughly 0.05 ppm, which is outnumbered and overwhelmed 400,000-to-one by NATURAL greenhouse gasses. Man-made CO2 (mainly from burning hydrocarbons, etc) is insignificant! A TINY FRACTION of NATURAL VARIATION! Like a drop of water in a swimming pool! Effectively ZILCH!
p1st
Dear Science and Econ, Please post peer reviewed sources to your claims since this would debunk 150 years of climate basics. Sincerely, Everyone living on the planet
christopher
"syngas" sounds like a bogus invented term by someone who is selling snake-oil garbage and has no clue whatsoever about chemistry and the normal way to name real gasses...
Science and Econ
Sadly, there are people out there who feel that climate is wrapped up in a tidy little function with atmospheric CO2. NOTHING COULD BE FURTHER FROM THE TRUTH. Who would need a computer running at 8 quadrillion calculations per second when a crayon and a 3 by 5 card and a Keeling curve would suffice? Do I need to cite peer reviewed sources for THIS, too? Do I need a peer to calculate 2 + 2? Can you name the top 20 things that impact the climate? Do you get all your "science" from the United Nations bureaucrats?
Robert in Vancouver
An issue that's rarely considered is the raw materials that go into making "green" energy devices. Windmills, solar panels, and artificial leaves require lots of raw materials that are mined then converted into metal, plastic, coatings, concrete, etc. After those devices wear out or get out-dated they are thrown away. So all things considered, "green" energy isn't any better for the environment than just burning nat gas or using oil.