▎ 摘　　要

Silver nanoparticles embedded reduced graphene oxide (rGO-Ag) nanocomposites are synthesized by green technique using clove leaf aqueous extract as reducing agent. The surface plasmon resonance (SPR) peak of silver nanoparticles (Ag NPs) at 410 nm in rGO Ag nanocomposites is analysed by UV-visible spectroscopy. The intensity of surface plasmon resonance (SPR) peak of Ag NPs in rGO-Ag nanocomposites is decreased with addition of Hg2+ ion at small interval of time. This is due to the occurrence of redox reaction between Ag-(0) and Hg2+ and also for the formation Ag/Hg amalgam. The lower limit of detection (LOD) of rGO Ag nanocomposites for Hg2+ ion is found to be 9.5 nM. Moreover, the rGO-Ag nanocomposites may be used as catalyst for degradation of methylene blue (MB) by sodium borohydride (NaBH4) at ambient temperature. The adsorption efficiency of methylene blue is increased due to hydrogen bonding and electrostatic interaction along with 7-7 stacking between the catalyst and the dye molecules. The methylene blue is degraded within a small time due to large surface area and more number of active sites of rGO-Ag nanocomposites. The as-synthesized nanocomposite is a potential hybrid material having dual activity as Hg2+ sensing and catalytic behaviour in degradation of methylene blue.