▎ 摘　　要

A simple, environmental benign, time and cost-efficient green approach has been proposed for the reduction of graphene oxide (GO) and the synthesis of reduced GO (rGO)/mono and bimetallic composites using Azadirachta indica extract. The high crystallinity and face-centred-cubic structure of monometallic silver (Ag) and bimetallic silver-gold (Ag-Au) nanoparticles anchored over rGO were determined from the X-ray diffraction patterns. The functional groups involved in the reduction of GO and metallic precursors were identified by the Fourier transform-infrared spectroscopic technique. The obtained morphological images revealed a homogeneous distribution of spherical shaped Ag/Ag-Au nanoparticles with a narrow size distribution anchored over the rGO sheets. The prepared nanostructures exhibited significant electrocatalytic activities towards the reduction of hydrogen peroxide (H2O2), leading to a non-enzymatic electrochemical sensor with a prompt amperometric response. The non-enzymatic sensor responded linearly (R-2 = 0.9970) to the concentration of H2O2 over a range of 0.1 to 5 mM with a low level detection limit of 1 mu M.