Graphene Solar Thermal Film Could Be a New Way To Harvest Renewable Energy

An anonymous reader quotes a report from IEEE Spectrum: Researchers
at the Center for Translational Atomaterials (CTAM) at Swinburne
University of Technology in Melbourne, Australia, have developed a
new graphene-based film that can absorb sunlight with an efficiency
of over 90 percent, while simultaneously eliminating most IR
thermal emission loss — the first time such a feat has been
reported. The result is an efficient solar heating metamaterial
that can heat up rapidly to 83 degrees C (181 degrees F) in an open
environment with minimal heat loss. Proposed applications for the
film include thermal energy harvesting and storage,
thermoelectricity generation, and seawater desalination. The 3D
structured graphene metamaterial (SGM) is composed of a
30-nanometer-thick film of alternating graphene and dielectric
layers deposited on a trench-like nanostructure that does double
duty as a copper substrate to enhance absorption. More importantly,
the substrate is patterned in a matrix arrangement to enable
flexible tunability of wavelength-selective absorption. The
graphene film is designed to absorb light between 0.28- to
2.5-micrometer wavelengths. And the copper substrate is structured
so that it can act as a selective bandpass filter that suppresses
the normal emission of internally generated blackbody energy. This
retained heat then serves to further raise the metamaterial’s
temperature. Hence, the SGM can rapidly heat up to 83 degrees C.
Should a different temperature be required for a particular
application, a new trench nanostructure can be fabricated and tuned
to match that specific blackbody wavelength. “The new material also
uses less graphene by significantly reducing the film thickness to
one third, and its thinness aids in transferring the absorbed heat
more efficiently to other media such as water,” the report adds.
“Additionally, the film is hydrophobic, which fosters
self-cleaning, while the graphene layer effectively protects the
copper layer from corrosion, helping to extend the metamaterial’s
lifetime.” The research is published in the journal Nature

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Source: *FS – All – Science News 2 Net
Graphene Solar Thermal Film Could Be a New Way To Harvest Renewable Energy