▎ 摘　　要

A facile green synthesis of silver nanoparticles (AgNPs) was achieved using aqueous leaf extract of Callicarpa Maingayi as a reducing and stabilizing agent during the synthesis from its salt solutions. The synthesized silver nanoparticles were analyzed with transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). XRD study shows that the particles are crystalline in nature with face centered cubic geometry. The crystallite size obtained from XRD is about 15 nm which is in agreement well with the TEM results. Anew nanostructure sensor was constructed by immobilizing silver nanoparticles and graphene oxide (AgNPs-GO) composite film on a glassy carbon electrode (AgNPs-GO/GCE). It was found that the AgNPs-GO composite exhibits good catalytic activity toward the reduction of hydrogen peroxide (H2O2), leading to an enzymeless sensor with a fast amperometric response time of less than 5 s, high selectivity, good reproducibility and stability. The linear range was 5.0 mu M to 700 mu M with a detection limit of 0.6 mu M (S/N = 3).