Synthesis Of Reduced Graphene Oxide Film By Reduction Of Graphene Oxide With Metal Iodide At Low Temperature

Since graphene has many potential applications due to its unique properties, it has become one of the most popular research topics recently. Obviously, the synthesis of high-quality graphene is one of most important research topics because it is closely related to practical applications. For now, many synthesis methods of graphene have been developed, such as mechanical exfoliation, chemical vapor deposition, reduction of graphene oxide (GO) and so on. Among all these methods, chemical reduction of graphene oxide is a promising route for large scale production of graphene at low cost.The basic route for chemical reduction of GO involves the oxidation of raw graphite, subsequent exfoliation of graphite oxide into individual GO sheets, and the in-situ chemical reduction of GO to form reduced graphene oxide (rGO), among which the process of chemical reduction of GO plays a key role that dominates the final quality of the rGo. Therefore, a reductive agent, which is low-cost, highly efficient and suitable for large scale production, is urged.Here we report a green and facile route for highly efficient reduction of free-standing GO papers with metal iodide aqueous solutions. The reductive ability of different metal iodide solutions with different pH values was studied. The reduction mechanism of these metal iodide solutions were discussed in detail. The metal iodides (MgI2, A1I3, ZnI2, FeI2) were synthesized directly from metal and iodine powder with water as a catalyzer. An extremely high bulk conductivity of55088S/m for rGO papers were obtained with FeI2solution of which pH=0at95℃for6hours. The catalytic effect of strong Lewis acid for the promotion of the nucleophilic substitution reaction is responsible for the greatly improved bulk conductivity. Furthermore, it was found that the layer-to-layer distance and the crystallinity of the rGO papers are regarded as two main factors affecting the bulk conductivity rather than C/O ratio and defect concentration.