Ionic liquid-induced synthesis of a graphene intercalated ferrocene nanocatalyst and its environmental application

Redox active processes between the π-conjugated system of ferrocene and graphitic surfaces of oxidized or reduced graphene oxide represent a growing area of interest for the development of tunable nanocatalytic systems. In this work, anchoring of intercalated cationic and anionic IL components that engage in both covalent and non-covalent interactions and the subsequent reorganization of IL–rGO bonds after ionothermal decomposition and water hydrolysis of reactive complexes suggests that IL functionalized rGO leads to a regional rearrangement of the carbon–carbon atomic network. The results of this study emphasize the combined solvent and templating properties of [BMIM][FeCl4] at the rGO–IL interface that synthetically directs the self-assembly of a non-hexagonal organometallic structural framework composed of nano-regimes of Fe(II) cyclopentadienyl ring complexes in a reduced graphene oxide matrix. The results show that the atomic rearrangement is consistent with the structural and behavioral characteristics of ferrocene. The capability of rGO-IL and its potential use as an environmental nanocatalyst was demonstrated by its ability to reversibly switch redox states between Fe(II) and Fe(III) corresponding to the ferrocene–ferrocenium redox pair permitting electron transfer from Fe to toxic Cr(VI) and its subsequent reduction to a non-toxic organometallic. A more general conclusion shows that the architectural geometry of the resulting solvated structure formed from the hybridization of ILs and rGO can be used to generate structurally driven properties that further diversify or impart new functionalities to graphitic structures by controlled synthesis from core materials. To the best of our knowledge, this is the first demonstration of a synthetic based approach for the assembly of ferrocene using the structure directing properties of ionic liquids and this route increases the scope of exploiting the electro-redox chemistry and potentially useful magnetic properties of ferrocene functionalized graphene hybrid materials for broader applications.