Carbon Honeycombs

What is made entirely of carbon but is not graphite, diamond, nanotubes, buckyballs, or sheets of graphene? According to a study by Nina V. Krainyukova and Evgeniy N. Zubarev of Ukraine’s National Academy of Sciences and National Technical University, respectively, the answer is carbon honeycombs (Phys. Rev. Lett. 2016, DOI: 10.1103/physrevlett.116.055501). The unusual carbon structures, which the researchers describe as three-dimensional graphene, form spontaneously when graphite rods are heated in a vacuum. The carbon undergoes sublimation, leading to the growth of carbon films 80- to 100-Å thick on a surface. The researchers analyzed the films via electron microscopy and high-energy electron diffraction. They also studied the material’s density, bonding, and capacity for storing noble gases, hydrogen, and carbon dioxide, which turned out to be roughly double the capacity of carbon nanotube bundles. Krainyukova and Zubarev conclude that the new material is composed entirely of sp²-bonded carbon with a periodic and nonperiodic structures that look like honeycombs.