Ultrathin Gold Nanowires: Soft-Templating versus Liquid Phase Synthesis, a Quantitative Study

Ultrathin Au nanowires were prepared following two routes: the reduction of the lamellar phase [OY-(AuCl)-Cl-I] in an excess of pure oleylamine and the direct reduction of Au-III in a solution of oleylamine in hexane. The superiority of the reduction of chloride gold precursor in isotropic environment is evidenced by small angle X-ray scattering (SAXS) measurements. A reaction yield of 75% is observed an order of magnitude higher than the route involving the lamellar phase. On the basis of a detailed SAXS analysis, the soft template role of the [OY-(AuCl)-Cl-I] intermediate solid phase was discarded for the nanowire growth. In the case of the liquid phase synthesis, density functional theory (DFT) calculations evidence a cooperative adsorption and organization of ions pairs at the surface of the ultrathin Au NWs. We propose that this charged backbone plays a key role in the unique growth mechanism of such anisotropic objects.