Influence of Modification with Iodine and Thermal Posttreatment on the Structure and Electrical Conductivity of Graphene Oxide

Abstract—An original technique for modifying graphene oxide with iodine has been developed. It is shown that, when graphene oxide is treated with iodine, oxygen-containing groups are removed from the surface of graphene planes, which improves the electrically conductive properties of the material. The change in the structure and electrical conductivity of the modified graphene oxide, depending on the concentration of iodine, has been studied. According to Raman spectroscopy data, it can be seen that the composition of the modified materials includes molecular complexes of iodine \({\text{I}}_{3}^{ - }\) and \({\text{I}}_{5}^{ - }\). Changes in the structure of the crystal lattice of iodine-modified graphene oxide films were studied using X-ray diffraction analysis. According to IR spectroscopy, the effect of iodination on the change in the qualitative composition of functional groups in the material was analyzed. The specific electrical conductivity of graphene oxide as a result of modification increases from 9.6 × 10^–10 S/cm for the original material to 3.3 × 10^–7 S/cm for the material treated with an isopropanol solution containing 1 wt % I₂ relative to dry graphene oxide. The additionally modified films were heat treated at 80°C for 2 h. The resulting changes in the structure of the material are analyzed and an increase in electrical conductivity by one or two orders of magnitude is shown.