Supersonic Spray Delivers
High-Quality Graphene Layer
A simple, inexpensive spray method that deposits a graphene film can heal manufacturing
defects and produce a high-quality graphene
layer on a range of substrates, report researchers at the University of Illinois at Chicago and
Their study is available online in the journal
Advanced Functional Materials.
Graphene, a two-dimensional wonder-materi-al composed of a single layer of carbon atoms, is
strong, transparent, and an excellent conductor
of electricity. It has potential in a wide range of
applications, such as reinforcing and lending
electrical properties to plastics; creating denser
and faster integrated circuits; and building better
Although the potential uses for graphene seem
limitless, there has been no easy way to scale up
from microscopic to large-scale applications without introducing defects, says Alexander Yarin, UIC
professor of mechanical and industrial engineering
and co-principal investigator on the study.
“Normally, graphene is produced in small
flakes, and even these small flakes have defects,”
Yarin says. Worse, when you try to deposit them
onto a large-scale area, defects increase, and
graphene’s useful properties — its “magic” — are
lost, he says.
Yarin first turned to solving how to deposit
graphene flakes to form a consistent layer without
any clumps or spaces. He went to Sam S. Yoon,
professor of mechanical engineering at Korea University and co-principal investigator on the study.
Yoon had been working with a unique kinetic
spray deposition system that exploits the supersonic acceleration of droplets through a Laval nozzle.
Although Yoon was working with different materials,
Yarin believed his method might be used to deposit
graphene flakes into a smooth layer.
Their supersonic spray system produces very
small droplets of graphene suspension, which
disperse evenly, evaporate rapidly, and reduce the
tendency of the graphene flakes to aggregate.
But to the researchers’ surprise, defects
inherent in the flakes themselves disappeared, as
a by-product of the spray method. The result was
a higher quality graphene layer, as found in the
analysis by another collaborator, Suman Sinha-Ray, senior researcher at United States Gypsum
and UIC adjunct professor of mechanical and
The researchers demonstrated that the
energy of the impact stretches the graphene and
restructures the arrangement of its carbon atoms
into the perfect hexagons of flawless graphene.
“Imagine something like Silly Putty hitting a
wall — it stretches out and spreads smoothly,”
says Yarin. “That’s what we believe happens with
these graphene flakes. They hit with enormous
kinetic energy, and stretch in all directions.”
Other attempts to produce graphene without
defects or to remove flaws after manufacture
have proved difficult and prohibitively expensive,
The new method of deposition, which allows
graphene to “heal” its defects during application, is
simple, inexpensive, and can be performed on any
substrate with no need for post-treatment, he says.
Nanotechnology Can Turn
Clothes Into Batteries
Imagine being able to carry all the juice you
needed to power your MP3 player, smartphone,
and electric car in the fabric of your jacket.
Sounds like science fiction, but it may become a reality thanks to breakthrough technology developed at a University of Central Florida
So far electrical
cables are used only
to transmit electricity.
However, nanotechnology scientist and professor Jayan Thomas and
his Ph.D. student Zenan
Yu have developed a
way to both transmit
and store electricity
in a single lightweight
Their work is the focus of the cover story of
the June 30 issue of the material science journal Advanced Materials, and science magazine
Nature has published a detailed discussion
about this technology.
“It’s an interesting idea,” Thomas says. “When we
did it and started talking about it, everyone we talked
to said, ‘Hmm, never thought of that. It’s unique.’”
Copper wire is the starting point but eventu-
ally, Thomas says, as the technology improves,
special fibers could also be developed with
nanostructures to conduct and store energy.
More immediate applications could be seen
in the design and development of electrical
Using a supersonic spray, graphene flakes with deformed pentagonal and heptagonal structures stretch on impact and spring into a perfect hexagonal graphene lattice.
This opens the way to scale up from the microscopic to large scale applications. Photo credit: Suman Sinha-Ray
Professor Jayan Thomas