Wireless device makes clean fuel from sunlight, CO2 and water

Date:
August 24, 2020
Source:
University of Cambridge
Summary:
Researchers have developed a standalone device that converts
sunlight, carbon dioxide and water into a carbon-neutral fuel,
without requiring any additional components or electricity.



FULL STORY ========================================================================== Researchers have developed a standalone device that converts sunlight,
carbon dioxide and water into a carbon-neutral fuel, without requiring
any additional components or electricity.


==========================================================================
The device, developed by a team from the University of Cambridge, is a significant step toward achieving artificial photosynthesis -- a process mimicking the ability of plants to convert sunlight into energy. It
is based on an advanced 'photosheet' technology and converts sunlight,
carbon dioxide and water into oxygen and formic acid -- a storable fuel
that can be either be used directly or be converted into hydrogen.

The results, reported in the journal Nature Energy, represent a new method
for the conversion of carbon dioxide into clean fuels. The wireless
device could be scaled up and used on energy 'farms' similar to solar
farms, producing clean fuel using sunlight and water.

Harvesting solar energy to convert carbon dioxide into fuel is a
promising way to reduce carbon emissions and transition away from fossil
fuels. However, it is challenging to produce these clean fuels without
unwanted by-products.

"It's been difficult to achieve artificial photosynthesis with a high
degree of selectivity, so that you're converting as much of the sunlight
as possible into the fuel you want, rather than be left with a lot
of waste," said first author Dr Qian Wang from Cambridge's Department
of Chemistry.

"In addition, storage of gaseous fuels and separation of by-products
can be complicated -- we want to get to the point where we can cleanly
produce a liquid fuel that can also be easily stored and transported,"
said Professor Erwin Reisner, the paper's senior author.



==========================================================================
In 2019, researchers from Reisner's group developed a solar reactor
based on an 'artificial leaf' design, which also uses sunlight, carbon
dioxide and water to produce a fuel, known as syngas. The new technology
looks and behaves quite similarly to the artificial leaf but works in
a different way and produces formic acid.

While the artificial leaf used components from solar cells, the new device doesn't require these components and relies solely on photocatalysts
embedded on a sheet to produce a so-called photocatalyst sheet. The
sheets are made up of semiconductor powders, which can be prepared in
large quantities easily and cost-effectively.

In addition, this new technology is more robust and produces clean
fuel that is easier to store and shows potential for producing fuel
products at scale. The test unit is 20 square centimetres in size,
but the researchers say that it should be relatively straightforward to
scale it up to several square metres.

In addition, the formic acid can be accumulated in solution, and be
chemically converted into different types of fuel.

"We were surprised how well it worked in terms of its selectivity --
it produced almost no by-products," said Wang. "Sometimes things don't
work as well as you expected, but this was a rare case where it actually
worked better." The carbon-dioxide converting cobalt-based catalyst
is easy to make and relatively stable. While this technology will be
easier to scale up than the artificial leaf, the efficiencies still need
to be improved before any commercial deployment can be considered. The researchers are experimenting with a range of different catalysts to
improve both stability and efficiency.

The current results were obtained in collaboration with the team of
Professor Kazunari Domen from the University of Tokyo, a co-author of
the study.

The researchers are now working to further optimise the system and
improve efficiency. Additionally, they are exploring other catalysts
for using on the device to get different solar fuels.

"We hope this technology will pave the way toward sustainable and
practical solar fuel production," said Reisner.


========================================================================== Story Source: Materials provided by University_of_Cambridge. The original
story is licensed under a Creative_Commons_License. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Qian Wang, Julien Warnan, Santiago Rodri'guez-Jime'nez, Jane
J. Leung,
Shafeer Kalathil, Virgil Andrei, Kazunari Domen, Erwin Reisner.

Molecularly engineered photocatalyst sheet for scalable solar
formate production from carbon dioxide and water. Nature Energy,
2020; DOI: 10.1038/s41560-020-0678-6 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200824123406.htm

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