Rapid green synthesis of silver nanoparticles and nanorods using Piper nigrum extract

We report sun light driven rapid green synthesis of stable aqueous dispersions of silver nanoparticles and nanorods at room temperature using photoreduction of silver ions with Piper nigrum extract. Silver nanoparticles were formed within 3 min of sun light irradiation following addition of Piper nigrum extract to the AgNO3 solution. The effects of AgNO3 concentration and irradiation time on the formation and plasmonic properties of biosynthesized silver nanoparticles were studied using UV-visible absorption spectroscopy. The morphology and structure of silver nanoparticles were well characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). The size of Ag nanoparticles increased with increase in irradiation time, leading to the formation of anisotropic nanostructures. Increasing the AgNO3 concentration resulted in the formation of Ag nanorods. UV-visible absorption studies revealed the presence of surface plasmon resonance (SPR) peaks which red shift and broaden with increasing AgNO3 concentration. We have demonstrated a facile, energy efficient and rapid green synthetic route to synthesize stable aqueous dispersions of silver nanoparticles and nanorods.