Room temperature ionic liquid assisted synthesis of ultra-stable Au nanoparticles via a modified Brust–Schiffrin method

Abstract

Au nanoparticles with a small size, narrow size distribution and extraordinary colloidal stability were synthesized via a modified Brust–Schiffrin two phase method. Hydrophobic phosphorus based room temperature ionic liquids (RTIL) were introduced into the toluene phase and solely used as both phase-transfer agent and stabilizer, which significantly simplified the two-phase synthetic system. The synthesized Au nanoparticles are stable for more than two years. Even the thoroughly dried Au NPs can be easily re-dispersed in toluene. Surface characterizations of the Au@RTIL nanoparticles revealed that the amount of the adsorbed RTIL molecules and their degree of order on Au surfaces as well as their interactions with Au surfaces determine the size and stability of the Au@RTIL nanoparticles. The synthetic method and the mechanism presented here are of great importance to the development of the BS method, as well as the Au nanoparticle synthesis and applications.