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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 N E 2 0 1 6
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CACTUS-LIKE MEMBRANE
BOOSTS FUEL CELL
EFFICIENCY
Researchers discovered a new
type of membrane that could poten-
tially boost the performance of fuel
cells and transform the electric vehicle
industry. The membrane, developed
by scientists from CSIRO, Australia,
and Hanyang University, Korea, fea-
tures a water-repellent skin, and can
improve the efficiency of fuel cells by
a factor of four when heated. Accord-
ing to Aaron Thornton at CSIRO, the
skin works in a similar way to a cactus
plant, which thrives by retaining water
in harsh and arid environments. “Fuel
cells, like the ones used in electric
vehicles, generate energy by mixing
together simple gases, like hydrogen
and oxygen. However, in order to main-
tain performance, proton exchange
membrane fuel cells need to stay con-
stantly hydrated,” says Thornton. This is
currently achieved by placing the cells
next to a radiator, water reservoir, and
humidifier, which require significant
space and power. The cactus-inspired
solution offers a new approach: Water is
generated by an electrochemical reac-
tion, which is then regulated through
nano-cracks within the membrane’s
skin. The cracks widen when exposed to
humidifying conditions and close when
it is drier. The result is fuel cells that can
remain hydrated without the need for
bulky external humidifier equipment.
For more information: Aaron Thornton,
, .
NANOTUBE SEMICONDUCTORS
IMPROVE PV SYSTEMS
Researchers at the National
Renewable Energy Laboratory (NREL),
Golden, Colo., discovered that single-
walled carbon nanotube semiconduc-
tors could be used in photovoltaic (PV)
systems because they can potentially
convert sunlight to electricity or fuel
without much energy loss. The research
builds on the work of Rudolph Marcus,
who developed a fundamental tenet
of physical chemistry that explains the
rate at which an electron can move
from one chemical to another.
In organic PV devices, after a
photon is absorbed, charges generally
need to be separated across an inter-
face so they can live long enough to
Cara Doherty examines a
cactus-inspiredmembrane.
BRIEF
Scientists from the DOE’s Brookhaven National Laboratory, Upton, N.Y., syn-
thesized ultrathin films containing multiple samples of a copper-oxide com-
pound to study its electronic behavior at near absolute zero. The technique
helps understand electron behavior as the material transitions from being an
insulator to a superconductor capable of carrying electric current with no
resistance.
Jie Wu, Anthony Bollinger, and Ivan Bozovic (left to right) load a sample in an apparatus capable
of reaching a temperature one-third of a degree above absolute zero.
ENERGY TRENDS
Nanotube semiconductors. Courtesy of
NREL.
be collected as electrical current. The
electron transfer event that produces
these separated charges comes with a
potential energy loss as the molecules
involved must structurally reorganize
their bonds. This loss is called reorga-
nization energy, but NREL research-
ers found little energy was lost when
pairing single-walled carbon nanotube
semiconductors with fullerene mole-
cules. “What we found is this particular
system—nanotubes with fullerenes—
has an exceptionally low reorganization
energy and the nanotubes themselves
probably have very, very low reorgani-
zation energy,” says Jeffrey Blackburn.