One-step synthesis of metal nanoparticle decorated graphene by liquid phase exfoliation

Abstract

A novel method for the fabrication of a metal nanoparticle (NP)–graphene hybrid based on the pristine graphene from liquid-phase exfoliation in organic solvents is essential. In the present work, 1-cyanoethyl-2-ethyl-4-methylimidazole (2E4MZ-CN) was employed as a novel stabilizer for graphene sheets in an acetonitrile solution and simultaneously as a reducing agent for metal NPs deposited on the graphene sheets. A homogeneous pristine graphene dispersion is achieved by sonication of natural graphite in an acetonitrile solution of 2E4MZ-CN. Once exfoliated from natural graphite under sonication, the graphene sheets can be stabilized by 2E4MZ-CN through the π–π interaction. Atomic force microscopy, Raman spectroscopy and transmission electron microscopy (TEM) confirm the presence of monolayer and few-layer graphene sheets. The absence of oxidation or destruction of the sp² character of the carbon is demonstrated by Raman spectroscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Silver NP (AgNP) decorated graphene hybrid is in situ synthesized during the curing process of epoxy resin. Scanning electron microscopy, X-ray diffraction and TEM show that the small particle size and good distribution of AgNPs are realized due to the stabilization of epoxy network. The synthesized AgNP decorated graphene is used as nanoscale filler to prepare highly conductive epoxy-based composites (4 × 10⁻⁵ Ω cm). The low temperature sintering of AgNPs attached on the graphene constructs effective electrical network in the epoxy matrix. This method facilitates the preparation of graphene-based materials for various applications.