Synthesis of graphene paper from pyrolyzed asphalt

A new technique for the synthesis of large sheets (>10 cm(2)) of multi-layered graphene is presented. The condensation onto a heated surface (approximate to 650 degrees C) of fumes from the thermal decomposition of asphalt in a ceramic crucible produces carbon films with a metallic sheen. Heating was done by a Fisher burner (natural gas/air) flame and the crucible was covered but exposed to laboratory atmosphere. These films were determined to be multilayered graphene by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), Raman and infrared spectroscopy and X-ray diffraction. XPS indicates that the films are primarily sp(2) hybridized carbon with small amounts of sp(3) C-H and C-O or C-N functionalities. Based on the D band shift (1593 cm(-1)) and the ratio of D band to G band (1354 cm(-1)) of 0.93, the Raman spectrum also indicates that the material is sp(2) C with some nanocrystalline features. The infrared spectrum exhibits A(1U) (868 cm(-1)) and E-1U (1599 cm(-1)) stretching of the intralayer bonds of graphene. This form of chemical vapor deposition may be a scalable to give much larger surface areas. Furthermore, the process does not require metal substrates. Deposition onto silica nanosprings and diatomites is demonstrated. (C) 2011 Elsevier Ltd. All rights reserved.