A scientist at the U.S. Department
of Energy's (DOE) Argonne National Laboratory has created visible-light
catalysis, using silver chloride nanowires decorated with gold nanoparticles,
that may decompose organic molecules in polluted water.
The gold-coated silver chloride nanowires at the microscopic level.
“Silver nanowires have been extensively studied and used for a variety
of applications, including transparent conductive electrodes for solar cells
and optoelectronic devices,” said nanoscientist Yugang Sun of Argonne’s
Center for Nanoscale Materials. “By chemically converting them into semiconducting
silver chloride nanowires, followed by adding gold nanoparticles, we have created
nanowires with a completely new set of properties that are significantly different
from the original nanowires.”
Traditional silver chloride photocatalytic properties are restricted to ultraviolet
and blue light wavelengths, but with the addition of the gold nanoparticles,
they become photocatalytic in visible light. The visible light excites the electrons
in the gold nanoparticles and initiates reactions that culminate in charge separation
on the silver chloride nanowires. Tests have already shown that gold-decorated
nanowires can decompose organic molecules such as methylene blue.
“If you were to create a film of gold-decorated nanowires and allow polluted
water to flow through it, the organic molecules may be destroyed with visible
irradiation from conventional fluorescent light bulbs or the sun,” Sun
said.
Sun started with traditional silver nanowires that were oxidized with iron
chloride to create silver chloride nanowires. A sequential reaction with sodium
tetrachloroaurate deposited the gold nanoparticles on the wires.
Sun said it is possible to use a similar mechanism to deposit other metals
such as palladium and platinum onto the silver chloride nanowires and create
new properties, such as the ability to catalyze the splitting of water into
hydrogen with sunlight.
A paper on this research was published in the Journal of Physical Chemistry
C.
Funding was provided by the U.S. Department of Energy Office of Science.