Uniform and monodisperse CuO nanorods have been synthesized by directional aggregation and crystallization of tiny CuO nanoparticles generated from a solid-liquid arc discharge process under ambient conditions in the absence of any surfactants. Uniform CuO nanorods with sharp ends are formed from tiny nanoparticles via a process that involves the rapid oxidation of Cu nanoclusters, the spontaneous aggregation of CuO nanoparticles, and the Ostawald ripening process. The spontaneous aggregation and oriented attachment of tiny CuO nanoparticles contributed obviously to the formation of these kinds of nanostructures. By choice of suitable reducing agent to prevent the oxidation of Cu nanoclusters, Cu and Cu2O nanoparticles can be selectively synthesized.
Mesostructured wurtzite ZnS‐nanowire‐bundle/amine nanocomposites displaying remarkable quantum size effects are synthesized by using a mild‐solution reaction using different amines, such as n‐butylamine, ethylamine, and tetraethylenepentamine, Zn(NO3)2·6 H2O, and CS(NH2)2 or Na2S·9 H2O as the precursors at temperatures ranging from room temperature to 180 °C. A possible mechanism for the shape‐controlled growth of ZnS nanowires and nanocomposites is proposed. Increasing the reaction temperature or dispersing the composite in acetic acid or NaOH solution leads to the destruction of the periodic structure and the formation of individual wurtzite nanowires and their aggregates. The nanowire/amine composites and individual wurtzite nanowires both display obvious quantum size effects. Strong band‐edge emission is observed for the wurtzite ZnS nanowires after removal of the amine. The optical properties of these nanocomposites and nanowires are strongly related to the preparation conditions and can be finely tuned. This technique provides a unique approach for fabricating highly oriented wurtzite ZnS semiconductor nanowires, and can potentially be extended to other semiconducting systems.
Highly uniform CdTe nanowires with a very high aspect ratio of approximately 1000 and an average diameter of 12 nm can be conveniently synthesized using ultrathin Te nanowires as templates via a low-temperature hydrothermal process. Several other interesting CdTe nanostructures, including tadpolelike, chainlike, and branched nanostructures, can also be fabricated by adjusting precursor concentrations and reaction temperature. The formation mechanism of uniform CdTe nanowires using highly reactive ultrathin Te nanowires as template has been discussed. The synthesized uniform CdTe nanowires can be well-dispersed in water or ethanol, and they may find potential applications in the fields of photovoltaics, biological sensors, and nanoscale electronics. The present templating method can also be extended to synthesize other one-dimensional telluride nanostructures such as PbTe nanowires with uniform diameter and high aspect ratios.
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