The Preparation And Purification Of One-Dimensional Gold Nanostructures

Au nanostructures exhibit unique physicochemical properties.Among these unique properties,the optical properties origined from surface plasmon resonance?SPR?are highly dependent on the size,composition and morphology of nanostructures.In various Au nanostructures,the one-dimensional nanostructures,such as nanorods and nanobipyramids,exhibit tunable SPR properties and have promissing application in a wide fields of sensing,biomedicine and optoelectronics.Therefore,controlled preparation of one-dimensional Au nanostructures is particularly important in fundamental research.In this work,seed-mediated method has been applied to synthesize one-dimensional Au nanostructures with different morphologies.The experimental parameters and the optical properties of nanostructures were studied.The growth mechanism of the obtained nanostructures have been discussed.The main work of this paper is listed as following:1.Synthesis of Au nanorods.Au nanorods with high purity have been synthesized via seed-mediated method.And the aspect ratio of Au nanorods can be tuned by altering the amount of seed and AgNO₃ in the growth solution.It is found that the surfactant in the growth solution not only plays the role of soft template,but also regulates the growth rate of nanostructures.2.Synthesis of Au nanobipyramids.The Au nanobipyramids have been prepared by a seed-mediated method,and the purity of Au nanobipyramids can be tuned by changing the ripening temperature of seed and type of surfactant in seed solution,respectively.The experimental results show that the heat treatment is beneficial to the transformation of single-twinned crystals to 5-fold twinned crystals.Trisodium citrate is beneficial to the transformation of single crystals to twinned crystals.The high rate of reaction is beneficial to the formation of twinned crystals.The main effect of CTAC is to keep the size of the seeds small enough to allow Ostwald ripening at the initial heat treatment stage.Finally,the mechanism of structure transformation is proposed.3.The purification of Au nanobipyramids.The Au nanobipyramids have been purified by utilizing NaCl,BDAC,TDBAC and Au@Ag bimetallic nanorods,respectively.