Shape-controlled synthesis for silver: Triangular/hexagonal nanoplates, chain-like nanoplate assemblies, and nanobelts
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ujian Zhao,b) Yuanzhi Li, and Xiaotao Sui Key Laboratory of Silicate Materials Science and Engineering, Wuhan University of Technology, Ministry of Education, Hongshan District, Wuhan, Hubei 430070, People’s Republic of China (Received 11 January 2009; accepted 17 March 2009)
Individual triangular/hexagonal nanoplates, chain-like nanoplate assemblies, and nanobelts in the case of silver were selectively synthesized using N,N-dimethylformamide (DMF) in the presence of poly (vinyl pyrrolidone) (PVP). The molar ratio of AgNO3/ PVP, concentration of AgNO3, temperature, and process time were crucial factors in determining the morphologies of the final products. Based on the experimental results, it was concluded that the products were favorable to form individual nanoplates because of the strong interaction between PVP and Ag+, and the outline of the nanoplates was controlled by the ratio of AgNO3 and PVP. The formation of novel chain-like nanoplate assemblies could be explained by the secondary growth of the nanocrystals. If the reaction continuously lasted for another 7 h, the chain-like assemblies could transform into nanobelts with width of 40100 nm and the length of several micrometers. I. INTRODUCTION
Nanostructured materials have attracted much attention because of their unique chemical and physical properties, which may have extensive applications in optics, electronics, catalysis, and fabrication of the nanoscale devices.1–4 These properties are strongly dependent on the size and shape of the nanomaterials, and therefore, control over the morphologies of the nanomaterials is important to their applications.5–9 Noble metals in nanoscale display characteristic absorption resulting from the surface plasmon resonances (SPRs), which largely depend on their shapes and sizes,10–17 and nanostructured silver was widely studied because of its excellent electrical and thermal conductivity among all metals. There have been many reports focused on the synthesis and characterization of onedimensional silver nanowires, nanobelts and nanotubes; two-dimensional nanoplates and nanodisks; and threedimensional nanocubes, nanodecahedrons, and nanospheres.18–30 For instance, macroporous membranes, mesoporous materials, carbon nanotubes, DNA channels, and organic nanotubes arrays were generally used as physical templates to guide the growth of silver Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/JMR.2009.0264 2200
J. Mater. Res., Vol. 24, No. 7, Jul 2009
nanowires.18–22 Sun and Xia23 developed a polyolprocess to obtain large-scale uniform silver nanowires using poly (vinyl pyrrolidone) (PVP) as a structuredirecting reagent. Our group recently synthesized zigzag silver nanowires using N,N-dimethylformamide (DMF) in the presence of tetrabutyl titanate (TBT) and acetylacetone (AcAc).24 Wei et al.25 reported an organic-assist solvothermal technique to synthesize silver nanotubes in high yield. Silver triangular nanoplates and nanobelts could be obtained by refl
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