Distribution of oxygen functional groups of graphene oxide obtained from low-temperature atomic layer deposition of titanium oxide

The distribution of oxygen functional groups on the surface of graphene oxide (GO) has been investigated experimentally and theoretically. Atomic layer deposition of TiO_x was used to clarify the location of oxygen functional groups. We found that the oxygen functional groups are distributed in the form of islands, which is confirmed using aberration corrected transmission electron microscopy and X-ray photoelectron spectroscopy. The density functional studies further support these findings. The evolution of oxygen functional groups was also investigated with GO treated at 150, 200, 250, and 300 °C. In addition, the reduction of epoxide and hydroxyl groups on the GO surface at different temperatures has been discussed in connection with ab initio molecular dynamics simulations.