October 12, 2012
Researchers Create Nanoflowers Of Germanium Sulfide For Next-generation Energy Storage
April Flowers for redOrbit.com - Your Universe Online
The GeS flowers have extremely thin petals, 20-30 nanometers thick, with an enormous surface area. These flowers hold promise for next-generation energy storage devices and solar cells.
“Creating these GeS nanoflowers is exciting because it gives us a huge surface area in a small amount of space,” says Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State. “This could significantly increase the capacity of lithium-ion batteries, for instance, since the thinner structure with larger surface area can hold more lithium ions. By the same token, this GeS flower structure could lead to increased capacity for supercapacitors, which are also used for energy storage.”
The team first heats GeS powder in a furnace until it begins to vaporize. This vapor is then blown into a cooler area of the furnace. The GeS settles out of the air into a layered sheet, 20 to 30 nanometers thick and 100 micrometers long. The flower forms as additional layers are added and the sheets branch out from one another in a floral pattern similar to a marigold or a carnation.
“To get this structure, it is very important to control the flow of the GeS vapor,” Cao says, “so that it has time to spread out in layers, rather than aggregating into clumps.”
Like graphite, GeS settles into neat layers or sheets. Unlike graphite, GeS's atomic structure makes it very good at absorbing solar energy and converting it into usable power. These abilities make it attractive for use in solar cells, particularly since GeS is relatively inexpensive and non-toxic. Many materials currently in use for solar cell technology are both expensive and extremely toxic.
The findings of this study have been published in the journal ACS Nano.