Perovskites can help to cheaply and effectively to produce hydrogen from water

Australian
the materials scientists have learned to effectively
to
hydrogen from water without
the use of expensive
of semiconductor materials.
They used the photocathode of
textured
silicon and
combined it with a wide-gap perovskite
solar cell, placing solar
elements below each other. Efficiency
the conversion of solar energy into
the hydrogen was
17.6 percent.
Results
research published
in the journal Advanced
Energy Materials.

Use
solar
energy
to produce hydrogen from water
the technology in the future
will solve two problems simultaneously:
storage of an unstable sun
energy for the future and for environmentally
clean fuel
high energy density.
For
output
on the market such converters have
to show the effectiveness of at least 20
percent, when the cost of hydrogen is not
above 4
dollars for
pounds.
Use
solar energy to produce hydrogen
in several ways.
In
photovoltaic converters
a solar cell connected to the cell
for electrolysis, and sunlight
is converted into electricity,
which
spent
electrolysis
water
solutions
with the formation of hydrogen and oxygen
the electrocatalysts.
In
photoelectrochemically converters
one or both electrodes consist of
of semiconductor materials. When
the irradiation light in the semiconductor
formed electrons and holes, which
directly involved in the reactions of education
of hydrogen and oxygen.
Considered
what photoelectrochemical converters
in the future will be cheaper (they
uses cheaper catalysts),
but have these devices and serious
disadvantage.
Case
is that better
just to produce hydrogen suitable
semiconductors with wide forbidden
zone of about 2 electron volts.
However,
this
a semiconductor absorbs only the
shortwave (high-energy)
part of the solar
radiation
therefore, the total
efficiency
devices a priori
will
low.
For
to overcome this problem, you can connect
the photoelectrode with a solar cell —
that is essentially to combine photovoltaic
and photoelectrochemical Converter
in a single device.
In
this case solar
the element provides current
and voltage
displacement, and
the conversion efficiency increases.
Scientists
managed
to tandem photoelectrochemical Converter
on the basis of gallium arsenide
with
effectiveness
19 percent.
But because of the high cost of gallium arsenide
gallium
such converters are not suitable for
industrial use.

Material engineers
under the guidance of Shiva Krishna Karuturi (Siva Krishna Karuturi) and
Hapina Shen (Shen Heping) from the Australian National
University have developed a tandem photoelectrochemical
Converter
without
the use of gallium arsenide and other
expensive semiconductors.
The photocathode they
did
from the n-type silicon
with
surface
textured in the form of pyramids is
improves light absorption and increases
the area of contact with the electrolyte solution. On
side
electrode, which was immersed in
the solution, caused
thin
a layer of platinum
catalyst
and
on the opposite
the side that
absorbed sunlight
the antireflective coating of
silicon nitride and metal
contacts.
When
this
silicon photocathode absorbs solar
radiation, its conduction band
generates electrons which
then react
with
cations
N+,
restoring
their
to molecular hydrogen.

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