German scientists say they have created a network of porous carbon tubes that is three-dimensionally interwoven at nano and micro level. It is described as the lightest material in the world and could be used as an additive to boost the conductivity of plastics without increasing their weight.
At 0.2 milligrams per cubic centimeter, it is described as 75 times lighter than Styrofoam—yet still very strong. Scientists of Kiel University (KU) and Hamburg University of
Technology (TUHH) have named their invention “Aerographite”.
Key properties: It is jet-black, stable, electrically conductive, and ductile. “Aerographite weighs four times less than the world-record-holder up to now”, says Matthias Mecklenburg, co-author and Ph.D. student at the TUHH. “Also, we are able to produce tubes with porous walls. That makes them extremely light”, adds Arnim Schuchard, co-author and Ph.D. student at Kiel University. Professor Lorenz Kienle and Dr. Andriy Lotnyk analyzed the material’s atomic structure with the aid of a transmission electron microscope (TEM).
Aerographite is able to be compressed up to 95% and be pulled back to its original form without any damage, says professor Rainer Adelung of Kiel University. “Up to a certain point the Aerographite will become even more solid and therefore stronger than before.”
A zinc oxide in powder form was heated up to 900ºC to become crystalline. The zinc-oxide was then formed into micro and nano structures (tetrapods) in a pill-type structure. That network is the basis for Aerographite. The pill is then positioned into the reactor for chemical vapor deposition and heated up to 760ºC. In a streaming gas atmosphere enriched with carbon, the zinc oxide receives a graphite coating of a few atomic layers. Then, hydrogen is introduced. It reacts with the oxygen in the zinc oxide and results in the emission of steam and zinc gas. What’s left is an interwoven, tube-like carbon structure.
Aerographite could fit onto the electrodes of Li-ion batteries, reducing weight. It could also be used to enhance the electrical conductivity of plastics. Other possibilities are under investigation.