Soft synthesis of single-crystal copper nanowires of various scales

Single-crystal copper nanowires (Cu NWs) have been synthesized by a series of simple hydrothermal methods. In this study, we will give several soft synthesis routes to fabricate low-dimensional nanocrystals with focus on various kinds of nanowires. Especially, Cu NW products with diameters around 6-10 nm and lengths below 1 pm can be obtained by using mesoporous silica (SBA-15) powders as templates through vapor infiltration of a reducing agent (dimethylamine borane, DMAB) under mild conditions; ethylene glycol reduction of copper nitrate at 160 degrees C in the presence of polyvinyl pyrrolidone (PVP, K-30) to prepare uniform copper nanowires, the average diameter of products is 30-50 nm and their lengths vary between 5 and 20 mu m; moreover, the products with Cu@C core-shell structure of 70-130 nm diameters and lengths longer than 10 mu m have been synthesized by using glucose as the reducing agent and the source of carbonaceous shells to react with copper(II) sulfate trihydrate (pentahydrate) under cetyltrimethylammonium bromide (CTAB) inducement. The morphology, microstructure and composition of the copper nanowires were characterized by scanning electron microscopy (SEM), tunneling electron microscopy (TEM) and X-ray diffraction (XRD). The effects of the different reaction conditions were investigated and their possible growth mechanisms are discussed. Beyond, so-called soft methods are soft-chemical, straightforward, and general approach, which have advantages for the synthesis of metal nanowires in large amounts.