Robust nanocomposites of α-Fe2O3 and N-doped graphene oxide: Interfacial bonding and chemisorption of H2O

Nanocomposites of alpha-Fe2O3 (hematite) and (N-doped) graphene oxide (GO) were investigated using first-principles calculations with focus on structure, chemical bonding, electronic structure and H2O adsorption. The nanocomposites were modeled as the interface between the alpha-Fe2O3 (0 0 0 1) surface and the basal plane of reduced graphene oxide, comprising epoxy groups (C:0 ratio of 8) as well as graphitic and pyridinic nitrogen doping. The composite structures exhibited strong chemical bonding by the formation of a bridging Fe-O-C bond. The calculated binding energy between the materials was -0.56 eV per Fe-O-C bond for GO and up to -1.14 eV for N-doped GO, and the binding energies were found to correlate with the charge of the bridging oxide ion. The composites exhibited partly occupied carbon states close to or above the alpha-Fe2O3 valence band maximum. Dissociative adsorption of H2O was found to be more exothermic for the composites compared to the individual materials, ranging from about -0.9 to -1.7 eV for the most stable configurations with hydroxide species adsorbed to GO and protons forming NH groups or adsorbed to the alpha-Fe2O3 surface. (C) 2019 The Authors. Published by Elsevier Ltd.