Water-Phase Synthesis of Ultrathin Au Nanowires with a Two-Dimensional Parallel Array Structure

Abstract

Ultrathin Au nanowires (NWs) with a diameter below 2 nm have attracted considerable attention as a promising onedimensional nanomaterial. However, they are practically synthesized in organic solvents. Here, for the first time, we report the synthesis of ultrathin Au NWs with ∼1.7 nm diameter in water using a water-soluble long-chain amidoamine derivative (C18AA) as a key compound. The resultant Au NWs were naturally dispersible in water, which is an environment-friendly solvent. We also demonstrate that the formation of the Au NWs is based on oriented-attachment growth mechanism, and that the presence of Cl ion facilitates its effective elongation over a length of a few μm. Further, cryogenic transmission electron microscopy (cryo-TEM) of the aqueous dispersion revealed that the Au NWs self-assembled into a bundle structure with two-dimensional parallel arrays in water.