Three-dimensional activated graphene network-sulfonate-terminated polymer nanocomposite as a new electrode material for the sensitive determination of dopamine and heavy metal ions

We report here that three-dimensional activated graphene networks (3DAGNs) are a better matrix to prepare graphene-polymer nanocomposites for sensitive electroanalysis than two-dimensional graphene nanosheets (2DGNs). 3DAGNs were synthesized in advance by the direct carbonization and simultaneous chemical activation of a cobalt ion-impregnated D113-type ion exchange resin, which showed an interconnected network structure and a large specific surface area. Then, the 3DAGN-sulfonate-terminated polymer (STP) nanocomposite was prepared via the in situ chemical co-polymerization of m-aminobenzene sulfonic acid and aniline in the presence of 3DAGNs. The 3DAGN-STP nanocomposite can adsorb dopamine (DA) and heavy metal ions, which was confirmed by quartz crystal microbalance studies. The 3DAGN-STP modified glassy carbon electrode (GCE) was used for the electrochemical detection of DA in the presence of ascorbic acid and uric acid, with a linear response range of 0.1-32 mu M and a limit of detection of 10 nM. In addition, differential pulse voltammetry was used for the simultaneous determination of Cd2+ and Pb2+ at the 3DAGN-STP/GCE further modified with a bismuth film, exhibiting linear response ranges of 1-70 mu g L-1 for Cd2+ and 1-80 mu g L-1 for Pb2+ with limits of detection of 0.1 mu g L-1 for Cd2+ and 0.2 mu g L-1 for Pb2+. Because the 3DAGN-STP can integrate the advantages of 3DAGNs with STPs, the 3DAGN-STP/GCE was more sensitive than the bare GCE, 3DAGN/GCE, and 2DGN-STP/GCE for the determination of DA and heavy metal ions.