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 μM 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 μg L−1 for Cd2+ and 1–80 μg L−1 for Pb2+ with limits of detection of 0.1 μg L−1 for Cd2+ and 0.2 μg 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.