Construction of strong alkaline hydrothermal environment for synthesis of copper telluride nanowires

Strong alkaline hydrothermal environment was constructed through adjusting the KOH concentration in solution for the synthesis of Cu_2−xTe nanocrystals. The Cu_2−xTe nanowires were successfully obtained by hydrothermal method without using any template or capping agent. The as-synthesized nanowires were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). The Cu_2−xTe nanowires with lengths up to hundreds of micrometers have a single crystal hexagonal structure and grow along the [11], [12], [13], [14], [15], [16], [17], [18], [19] and [20] direction. A growth mechanism was proposed based on the characterization results. The energy gap of as-synthesized Cu_2−xTe nanowires is ca.1.1 eV for direct band transition or 0.7 eV for indirect band transition. The structural phase transformations occur at 322, 353 and 477 °C. And the Cu_2−xTe nanowires exhibit the metal electrical conductivity.