Obtaining ultra-long copper nanowires via a hydrothermal process

Ultra-long and uniform copper nanowires with controllable diameters of 30-100 nm, length up to several millimeters (aspect ratio >105) and tunable crystallinity were obtained by hydrothermal processing the complex emulsion of copper (II) chloride and ODA at 120-180 °C. Both XRD pattern and EDX spectrum indicated that the products were pure copper without any observable impurities. It is observed by FESEM that the diameters and aspect ratios of the synthesized copper nanowires were influenced by the concentration of ODA and reaction temperature. HRTEM images and SAED patterns revealed that the crystallinity of copper nanowires were strongly dependent on the synthesis temperatures. Poly- and single-crystal copper nanowires were obtained at 120 °C and 180 °C, respectively.