科研之友
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摘要
An alkylamine-mediated hydrothermal synthesis method is proposed for fabrication of copper (Cu) nanopolyhedrons (including tetrahedral and cubic shapes) with well-defined facets and controllable size by modulating the coordination chemistry of a sole ligand (hexadecylamine, HDA) or dual ligands [HDA and octadecylamine (ODA)]. The size of the nanopolyhedrons increases with decreasing HDA/ODA mole ratio. Both the nanocubes and nanotetrahedrons are single-crystal structures, bound by six {100} or four {111} facets, respectively. The complexation reaction temperature plays a vital role in determining the final morphology of the as-prepared nanocrystals. High complexation reaction temperature is suitable for generation of single-crystalline Cu nuclei and their further growth into nanocubes and nanotetrahedrons, while low temperature leads to formation of multitwinned crystal seeds that finally develop into nanowires. Moreover, the probable aggregative growth is discussed to explain the growth mechanism of the Cu nanopolyhedrons. In addition, double surface plasmon resonance peaks are observed in the absorbance spectra for the Cu nanopolyhedrons with relatively large size. Finite-difference time-domain simulations reveal that the experimental absorption spectra are the superposition of those for nanocubes and nanotetrahedrons in different proportions. The peak at about 600 nm in the experimental spectra mainly originates from the Cu nanocubes, while the absorption from 750 to 950 nm derives from the Cu nanotetrahedrons. These angular Cu nanocubes and nanotetrahedrons may have potential applications in surface-enhanced Raman scattering and catalysis. [GRAPHICS] .
