Highly dispersed graphene oxide-silver nanoparticle composites in organic solvents

Abstract

An innovative phase transfer process of anisotropic silver nanoparticles (AgNPs) from water to a wide range of organic solvents such as toluene, n-butanol, iso-butyl acetate, ethyl acetate, acetonitrile and ethylene glycol was described. In the developed process, AgNPs were transferred to the organic solvents by using the graphene oxide (GO) sheets as the carrier. The transferring process was utilized by two straightforward steps. Firstly, AgNPs were synthesized using N-N' dimethylformamide (DMF) as a reducing agent and they were stabilized by the numerous of oxygen-functional groups on the GO surface via electrostatic interaction to form GO/AgNP composites. The existence, purity and stability of AgNPs on the GO sheets were examined and analyzed by several techniques such as UV-Visible spectroscopy (UV-Vis), Fourier-transform Infrared (FT-IR) spectroscopy, Raman spectroscopy, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Secondly, the GO/AgNP composites were modified with oleylamine (OAm) in order to improve hydrophobicity. To obtain the maximum phase transfer efficiency, an appropriate amount of OAm was carefully optimized for each organic solvent. The dispersion behavior of the GO/AgNP composites modified with OAm (GO/AgNP-OAm) in the organic solvents were investigated. It was found that the GO/AgNP-OAm are uniformly dispersed in the organic solvents for at least 6 hours after sonication. The developed phase transfer method has the features of simplicity and high efficiency.