Ultrasmall Copper Nanoparticles Synthesized with a Plant Tea Reducing Agent

Ultrasmall copper nanoparticles were synthesized using lemongrass tea as a green reducing agent. The one-pot, aqueous, room-temperature reaction produces nanoparticles with diameters of 2.90 +/- 0.64 nm. UV-vis spectroscopy shows the ultrasmall nanoparticles are nonplasmonic. FTIR spectroscopy indicates that oxygen-containing functional groups in the lemongrass tea are present in the nanoparticle reaction mixture. High-resolution transmission electron microscopy (HR-TEM) was used to confirm that the nanoparticles are Cu, as indicated by the lattice spacing measurements for the (111), (200), and (220) lattice planes of Cu. The nanoparticles are transferrable from water to hexane with octadecanethiol (ODT) as a phase transfer agent. X-ray energy dispersive spectroscopy (EDS) conducted during TEM analysis confirms the presence of copper in the nanoparticle samples and indicates that the phase-transferred nanoparticles have relatively less material associated with lemongrass tea than the as-synthesized sol.