"Even very thin specimens of Aerographite are fully opaque for the eye," said Hamburg's Matthias Mecklenburg.
Unlike a sponge, which would "leak" or "glow" any light aimed at it, Aerographite is "not a bit transparent," he said.
But, he added, our hands would hardly register its "fluffy," spongelike surface, because the innovative material is practically weightless.
Electrically conductive and lighter than the previous titleholder—a nickel-based material introduced earlier this year—Aerographite has promising applications in the engineering of batteries and water-purification systems, as well as in biotechnology.
A scanning electron microscope view of Aerographite calls to mind cobwebs or a tangle of threads. In fact, this wispy form is a network of carbon ribbons and is one of many strutlike elements that together form a larger, porous network of "inner bridges."
This kind of hierarchical structure is what allows for the low density and high strength of Aerographite, Mecklenburg said.
To make Aerographite, powdered zinc oxide is heated in a furnace at 1,650 degrees Fahrenheit (900 degrees Celsius). The crystallized results are formed into a "pill," which contains microscopic and nanosize zinc oxide structures called tetrapods.
The tetrapods form the foundation for Aerographite. Next the pill is heated to 1,400 degrees Fahrenheit (760 degrees Celsius) in a carbon-laced gas atmosphere.
As Aerographite forms, wispy graphite shells hold the shapes of receding zinc oxide structures in a scanning electron microscope image. The structures "will remain after the process as part of the Aerographite," Mecklenburg said.
In addition to being ultralight, Aerographite is also extremely flexible and resilient. It can withstand almost complete compression without any damage, and its networks can be adjusted to accommodate different potential applications down the road, according to the new study, which appeared in the July issue of the journal Advanced Materials.