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A D V A N C E D
M A T E R I A L S
&
P R O C E S S E S | J U L Y / A U G U S T
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“Oxidation can lead to the for-
mation of a protective layer against
corrosion attack,” explains Guangwen
Zhou, associate professor of mechani-
cal engineering. “Our results establish
the principles of predicting the trend
for promoting or suppressing the oxi-
dation of materials.” This could allow
researchers to tailor a reaction for
corrosion resistance in copper water
pipes on one hand, or for improved
chemical catalysis on the other.
.
In situ atomic scale observation of
oxidation process of a copper surface
by transmission electron microscopy.
Courtesy of Guangwen Zhou.
Illustration shows concept of imaging
carbon defect areas using palladium
markers. Courtesy of Zelinsky Institute of
Organic Chemistry.
when smooth graphene is required, or
incorporating them when beneficial,
such as in catalysis. Using palladium
markers, the team determined that
more than 2000 surface defects can be
found on each square micrometer of
graphene surface area, challenging the
current understanding of the electronic
and structural properties of carbon
materials. .
A PALLADIUM PEEK AT
GRAPHENE’S INVISIBLE
DEFECTS
Researchers at the Zelinsky Insti-
tute of Organic Chemistry, Russia,
developed a new technique to map
carbon reactivity centers on the sur-
face of graphene. While these defects
are normally undetectable under an
electron microscope, the team used
palladium as a contrast agent, ren-
dering them visible. When graphene
was added to a solution of palladium
complex Pd2(dba)3 dissolved in chloro-
form, the palladium clusters selectively
attached to the surface of the graphene
according to how reactive the carbon
centers were: Individual palladium par-
ticles stuck to point defects, local accu-
mulations of particles rested on larger
defects, and short chains lay along lin-
ear defects.
Several types of defects are known
to increase the reactivity of graphene’s
carbon atom, and mapping these reac-
tivity centers is the first step toward
manipulating them—removing them