Structural phase modifications induced by energetic ion beams in graphene oxide

Different ion beams, with energy from 2 MeV up to 16 MeV at different atomic number, have been employed to irradiate graphene oxide (GO) foils in vacuum. Due to effects of electron and nuclear ion stopping powers, the ion energy deposition reduces the irradiated GO foils and structurally modifies them. The ion bombarded GO foils X-ray diffraction (XRD) investigations have permitted to shed light on the different structural phases induced by the ion energy deposition. The changes in the GO foils pristine structure shift the diffraction main peak towards larger angles and produce new diffraction peaks indicating the presence of new phases, such as reduced GO (rGO), carbon nanotubes (CNT), amorphous carbon (a-C), onion like carbon (OLC) and probably new carbon allotropes. The obtained results indicate that the inner structure of the GO foils becomes more and more compact and dense with the absorbed dose, suggesting that the removal of the functional oxygen groups leads to a near graphite structure with a significant increase of the material mass density. The different structural phase modifications induced by the different ion beams as a function of the stopping power, fluence and dose will be presented and discussed in detail.