"Think of the Aerographite as an ivy-web, which winds itself around a tree. And than take away the tree", Adelung describes the construction process. The "tree" is a so-called sacrificial template, a means to an end. The Kiel-team, consisting of Arnim Schuchardt, Rainer Adelung, Yogendra Mishra and Sren Kaps, used a zinc oxide in powder form. By heating this up to 900 degrees Celsius, it was transformed into a crystalline form.
From this material, the scientists from Kiel made a kind of pill. In it, the zinc-oxide formed micro and nano structues, so called tetrapods (illustration # 4). These interweave and construct a stable entity of particles that form the porous pill. In that way, the tetrapods produce the network that is the basis for Aerographite.
In a next step, the pill is positioned into the reactor for chemical vapour deposition at TUHH and heated up to 760 degrees Celsius. "In a streaming gas atmosphere that is enriched with carbon, the zinc oxide is being equipped with a graphite coating of only a few atomic layers. This forms the tanged-web structures of the Aerographite. Simultaneously, hydrogen is introduced. It reacts with the oxygen in the zinc oxide and results in the emission of steam and zinc gas", continues Schulte. The remains are the characteristic interwoven, tube-like carbon structure. TUHH-scientist Mecklenburg: "The faster we get the zinc out, the more porous the tube's walls get and the lighter is the material. There is consi
|Contact: Jutta Katharina Werner|