The physical structure and surface reactivity of graphene oxide

Abstract

The structural configuration of graphene oxide and its surface reactivity were investigated experimentally and clarified on the bases of time-independent density functional calculations (DFT). The physical structure was examined by transmission electron microscopy, infrared absorption, and X-ray diffraction parallel to radial distribution analysis. Surface reactivity was examined using N2-adsorption at 77 K and the kinetic of the adsorption of Ni2+, Cd2+, and Pb2+ ions at 300 K. The lattice structure of the material was hexagonal with unit cell a = 2.455 Å and c = 8.64 Å and with layer-layer distance of 4.32 Å. This structure is undulated in response to existence of oxygen atoms that shape surface topological imperfections and breaks the planner regularity. The undulation distance comprises 0.3 Å. The specific surface area was found 60.3 m2/g with about 50% of this area were available to adsorption of 2+ ions due to surface polarization. The vibration frequencies observed in FTIR are identified by DFT calculations and showed that the structure acts as an extended quantum system for which Pauli blocking prevents existence of two modes of marginal hydrogen vibrations within the same sheet.