Facile synthesis of reduced graphene oxide/silver nanoparticles composites and their application for detecting heavy metal ions

The poor incorporation between graphene sheets and Ag NPs has become a problem in the application of graphene based composites. In this paper, graphene oxide (GO) was functionalized with triethylene tetramine (TETA), and then reduced graphene oxide/Ag nanoparticles composites (RGO/Ag NPs) were prepared using TETA as the reductant via a hydrothermal method. TEM, SEM, XRD, FTIR, EDS and Raman spectra were used to investigate the morphologies and structures of as-prepared RGO/Ag NPs composites. The results showed that Ag NPs were successfully incorporated with RGO sheets and the completely separated RGO sheets were disordered. Compared with functionalized GO (FGO), the intensity ratio of D band to G band (I_D/I_G) for RGO/Ag NPs composites decreased, and I_D/I_G of F6G was 1.08. When the content of AgNO₃ solution increased, the Ag content in the composite also increased and that in F8G was 26.23 wt%. However, the size of Ag NPs in F8G remained small and that was in the range of 10–20 nm. Besides the good electrochemical performance according to the CV curves, the detection limit of the trace concentration of Cu²⁺, Cd²⁺ and Hg²⁺ for F8G was calculated to 10⁻¹⁵ M, 10⁻²¹ M and 10⁻²⁹ M, respectively. Although the detection limit for Cd²⁺ and Hg²⁺ had certain derivation, as-prepared RGO/Ag NPs composites can be used as the candidate of the sensors for detecting the trace of these heavy metal ions.