Dynamic dispersion stability of graphene oxide with metal ions

Graphene oxide (GO), an important chemical precursor of graphene, can stably disperse in aqueous surrounding and undergo aggregation as metal cations introduced. The usual instability of GO with ions is caused by the shielding effect of ions and crosslinking between GO and ions. However, the dynamic stability of GO under ions exchange still remains unclear. Here, we investigated the dynamic dispersion stability of GO with metal ions and observed a redispersion behavior in concentrated Fe³⁺ solution, other than permanent aggregation. The exchange with Fe³⁺ ions drives the reversion of Zeta (ζ) potential and enables the redispersion to individual GO-Fe³⁺ complex sheets, following a dynamic electric double layer (EDL) mechanism. It is found that the specifically strong electrostatic shielding effect and coordination attraction between Fe³⁺ and functional oxygen groups allows the selective redispersion of GO in concentrated Fe³⁺ solution. The revealed dynamic dispersion stability complements our understanding on the dispersive stability of GO and can be utilized to fabricate graphene-metal hybrids for rich applications.