Pairing of Pentagonal and Heptagonal Carbon Rings in the Growth of Nanosize Carbon Spheres Synthesized by a Mixed-Valent Oxide-Catalytic Carbonization Process

Abstract

Carbon spheres have been synthesized using a mixed-valent oxide-catalytic carbonization process in macroscopic quantities and at low cost. The technique uses natural gas and reusable catalysts and produces no environmental waste or pollution. The product is all solid spheres (∼210 nm) comprised of layered graphitic flakes. Microstructures of the spheres are studied by transmission electron microscopy. The sphere is believed to be nucleated from a pentagon carbon ring followed by a spiral shell growth. When the sphere grows larger, graphitic flakes are nucleated on the surface due to the formation of paired pentagonal−heptagonal (P−H) carbon rings. A combination of the P−H pairs with the hexagonal networks produces eight basic graphitic configurations for forming the sphere, and they have been observed experimentally.