In-situ synthesis of reduced graphene oxide/gold nanoparticles modified electrode for speciation analysis of copper in seawater.

In this paper, reduced graphene oxide/gold nanoparticle/Nafion (rGO/AuNP/Nafion) modified electrode was fabricated through in-situ synthesis and used for determination of copper ions in strong salt electrolyte (0.5M NaCl) by differential pulse anodic stripping voltammetry (DPASV). This in-situ synthesis procedure was based on the ion-exchange and electrochemical reduction. The use of rGO provided a larger electrode surface and the presence of more active sites, while electron transfer was accelerated by incorporating AuNPs. Nafion was utilized as a cation exchange polymer in which rGO and AuNPs could be tightly attached to the electrode surface. The physical and electrochemical characterizations of the as-prepared modified electrode were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and cyclic voltammetry. AuNPs with diameter of 5-10nm on rGO decorated in the gold electrode surface were observed. Under the optimal conditions, the rGO/AuNP/Nafion electrode had a linear response to copper ions in the concentrations range from 20nM to 1μM (R2 = 0.998), with the lowest detectable concentration of 8nM and the detection limit of 4nM (S/N = 3). Additionally, this electrode was successfully applied to the speciation analysis of copper (free, dissolved and total) in seawater.