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Rice University chemists make conductive
laser-induced graphene from wood
HOUS TON, TX – Scientists at Rice University
have made wood into an electrical conductor by turning its surface into graphene [ 1].
Rice chemist James Tour and his colleagues used carbon dioxide (CO2) laser
scribing to blacken a thin-flm laser-induced graphene (LIG) pattern onto a block
of pine. Laser-induced graphene was discovered at Rice in 2014.
Previous iterations of LIG were made
by heating the surface of a sheet of polyimide, an inexpensive plastic, with a laser.
Rather than a fat 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.
Not just any polyimide would produce
LIG, and some woods are preferred over
others, Tour says. The research team led
by Rice graduate students Ruquan Ye
and Yieu Chyan tried birch and oak, but
found that pine’s cross-linked lignocellulose structure made it better to produce
high-quality graphene than woods with a
lower lignin content. LIG has a high conductivity on the order of 10 Ω per square.
As with polyimide, the process takes
place with a standard industrial CO2 laser
at room temperature and pressure 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 fakes of graphene
foam bound to the wood surface.
Changing the laser power also changed
the chemical composition and thermal stability of the resulting LIG. At 70% power,
the laser produced the highest quality of
what they dubbed P-LIG, where the P
stands for pine.
The lab took its discovery a step further by turning P-LIG into electrodes for
splitting water into hydrogen and oxygen
and supercapacitors for energy storage.
For the former, they deposited layers of
cobalt and phosphorus or nickel and iron
onto P-LIG to make a pair of electrocata-lysts with high surface areas that proved
to be durable and effective.
Depositing polyaniline onto P-LIG
turned it into an energy-storing superca-
pacitor that had usable performance met-
rics, Tour says.
“There are more applications to
explore,” Ye says. “For example, we
could use P-LIG in the integration of solar
energy for photosynthesis. We believe this
discovery will inspire scientists to think
about how we could engineer the natu-
ral resources that surround us into bet-
would be sending it back to the ground
from which it came along with the wood
platform instead of to a landfll full of elec-
1. R. Ye et al., Adv. Mater. (2017); doi: 10.1002/
This article was written by John Wallace,
senior editor for Laser Focus World.
This Rice University athletics logo is made
of laser-induced graphene on a block of
pine; the scientists used an industrial laser
to heat the wood and turned its surface
into highly conductive graphene. The
material could be used for biodegradable
electronics. (Courtesy: Tour Group/Rice