Low temperature reduction of free-standing graphene oxide papers with metal iodides for ultrahigh bulk conductivity

Here we report a green and facile route for highly efficient reduction of free-standing graphene oxide (GO) papers with metal iodide aqueous solutions at low cost. The metal iodides (MgI(2), AlI(3), ZnI(2), FeI(2)) were synthesized directly from metal and iodine powder with water as a catalyzer. An extremely high bulk conductivity of 55088 S/m for reduced graphene oxide (rGO) papers were obtained with FeI(2) solution of which pH = 0 at 95°C for 6 hours. 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 (d(L)) 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. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1038/srep03965) contains supplementary material, which is available to authorized users.