| In recent years,nobel metal nanomaterials have been widely used in analytical detection,photothermal therapy,biological imaging and other fields due to their local surface plasmon resonance（LSPR）and photothermal conversion effect.The LSPR of nanomaterials is closely related to the morphology,structure,element composition and other physical parameters of nanomaterials.In order to meet the different needs of nanomaterials in different research fields,new structures nanomaterials or composite nanomaterials have been studied by reaseach.In addition,surface enhanced Raman scattering（SERS）technology is one of the most widely used analytical detection techniques in modern times.Its detection sensitivity and stability are highly dependent on the Raman substrate with good performance.Nanomaterials such as gold and silver have made great contributions to the development of SERS.Therefore,the preparation of new gold and silver nanomaterials will promote the application of SERS detection technology.In this research,the decahedral gold seeds were used as the crystal nucleus.The seed-mediated method were improved by using different surfactants or additives to prepared nobel nanomaterials with a variety of morphologies,sizes and structures.Finally,the prepared nobel nanomaterials are used to prepare Raman substrates for SERS detection.The specific research contents are as follows.（1）The decahedral gold nanoseeds were prepared by hydrothermal method.Using the decahedral gold nanoseeds as crystal nucleus,and using benzyldimethylhexadecylammoniu-m chloride（BDAC）as surfactant,gold nanoparticles with controllable size were prepared by seed-mediated method.In the experiment,the amount of seed solution,the amount of chloroauric acid,the reaction temperature and whether to add HCl or AgNO3 were discussed in detail.The gold nanoparticles with various morphologies were prepared,such as biconical,dumbbell,and elliptical and spherical,etc.In addition,the effect of reaction conditions on the morphology of Au nanodumbbells was investigated.It was found that the morphology of Au nanodumbbells are the result of the combined effect of the surfactant BDAC and the underpotential deposition of silver.Finally,Au nanodumbbells were used to detection of 4-Mercaptobenzoic acid（4-MBA）by SERS.The experimental results show that the detection range was 1×10-2-1 ×10-8 M.（2）Using the Au nanodumbbells prepared in the previous chapter as the crystal cores,a series of core-shell Au@Ag nanorods（Au@Ag NRs）with uniform size have been successfully prepared by the selective deposition of Ag on the nanorods.The results showed that the prepared Au@Ag NRs are surrounded by {111} and {100} crystal planes,and the deposited Ag is mainly distributed on the two ends of the Au nanodumbbells.With the increase of the amount of silver nitrate,the LSPR of the prepared nanorods can be controllably adjusted in the ultraviolet,visible and near infrared light band.The increase content of Ag in Au@Ag NRs is conducive to enhancing the Raman scattering intensity,but when the content of silver is too much,the SERS enhancement ability will slowed down The SERS detection range of core-shell Au@Ag（5）nanorods for 4-MBA is 1×10-4-1×10-12 M.（3）Combining the electrochemical displacement method and the co-deposition method,Au@Au/Ag nanoframes were successfully prepared by using Au@Ag nanorods as the template.The middle of the nanoframes is wrapped with Au nanodumbbells,and the nanoframes have obvious structures distributed at the two ends of the biconical gold nanorods.The key factors affecting the preparation of Au@Au/Ag nanoframes（Au@Au/Ag NFs）,such as reaction temperature,pH value,the amount of surfactants,and the amount of chloroauric acid were discussed in detail.By changing the amount of HAuCl4,the selective deposition position of Au on Au@Ag NRs were discussed.A series of nanomaterials with hollow structure were prepared.Finally,Au@Au/Ag NFs were used as SERS substrates and the detection range of SERS is 4-MBA is 1×10-3-1×10-9 M. |
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