graphene has been considered a wonder material for some time and many researchers are looking at new methods for creating the single atomic layer of carbon, including a group of chemists at rice university who turned the surface of a piece of wood into graphene, which turned the wood into an electrical conductor.
this rice university athletics logo is made of laser-induced graphene
on a block of pine. (tour group/rice university)
according to a report on the university website, chemists used a laser to blacken a thin film onto a block of pine, creating a patterned laser-induced graphene (lig), a material discovered at the school in 2014.
“previous iterations of lig were made by heating the surface of a sheet of polyimide, an inexpensive plastic, with a laser,” the article explained. “rather than a flat sheet of hexagonal carbon atoms, lig is a foam of graphene sheets with one edge attached to the underlying surface and chemically active edges exposed to the air.”
researchers tried birch and oak but were not as successful. pine’s cross-linked lignocellulose structure proved to be more effective at creating high-quality graphene.
this breakthrough leads researchers to believe that there are other methods for making graphene out of non-polyimide materials even at room temperature and in an inert argon or hydrogen atmosphere.
“without oxygen, heat from the laser doesn’t burn the pine but transforms the surface into wrinkled flakes of graphene foam bound to the wood surface,” the article continued. “changing the laser power also changed the chemical composition and thermal stability of the resulting lig. at 70 percent power, the laser produced the highest quality of what they dubbed ‘p-lig,’ where the ‘p’ stands for pine.”
after proving it was possible to make p-lig, the scientists added layers of cobalt and phosphorous or nickel and iron to make electrocatalysts with high surface areas. adding polyaniline to the p-lig turned it into an energy-storage supercapacitor.
the research was recently published in advanced materials. the abstract stated:
“wood as a renewable naturally occurring resource has been the focus of much research and commercial interests in applications ranging from building construction to chemicals production. here, a facile approach is reported to transform wood into hierarchical porous graphene using co2 laser scribing.
“studies reveal that the crosslinked lignocellulose structure inherent in wood with higher lignin content is more favorable for the generation of high-quality graphene than wood with lower lignin content. because of its high electrical conductivity (≈10 ω per square), graphene patterned on wood surfaces can be readily fabricated into various high-performance devices, such as hydrogen evolution and oxygen evolution electrodes for overall water splitting with high reaction rates at low overpotentials, and supercapacitors for energy storage with high capacitance.
“the versatility of this technique in formation of multifunctional wood hybrids can inspire both research and industrial interest in the development of wood-derived graphene materials and their nanodevices.”
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