Fabrication And SERS Characteristics Of The Hybrid Of RGO/Au@AgNRs

Surface-enhanced Raman Scattering?SERS?is a highly sensitive detection method,achieves rapid detection at the single-molecular level and widely used in fields such as environmental monitoring and food safety.The active substrates are the critical for SERS intensity.Graphene is suitable for the substrate due to the high-ratio areas,high conduction and flexibility.However,the sole graphene is not enough active for the SERS,and the its hybrid with metal nanoparticles can effectively solve this problem.In this thesis,we use a simple and low-cost method to combine the reduced graphene oxide?rGO?with Au@Ag core-shell nanorods?Au@AgNRs?as the SERS active substrate,which showed high sensitivity and stability.The hybrid active material rGO-Au@AgNRs can be used to detect the thiram residues at ultra-low concentration.The dissertation is mainly focused on:?1?Preparation of Au Nanorods?AuNRs?and Au core Ag shell Nanorods?Au@AgNRs?.Firstly,AuNRs are prepared in a seed method with CTAB as a template which display good dispersion,and then coat with Ag nano-layer through reducing AgNO₃.Finally,the Au@AgNRs with a distinguish core-shell structure are obtained.?2?The GO,prepared by modified Hummers method,has abundant negatively charged surface due to the functional groups?mainly-OH?,which easily combine with the positively charged Au@AgNRs.Subsequently,the above hybrid materials are reduced under hydrothermal-reduction and high-temperature annealing method.?3?The SERS test of the product rGO-Au@AgNRs are obtained by R6G with an enhancement factor reached to 5.06×10⁸.Depending on the activity SERS of the rGO-Au@AgNRs,the 10^-7 M?0.03ppm?of thiram is detected,which is much lower than the maximal residue limit?MRL?of 7 ppm in fruit prescribed by the U.S.Environmental Protection Agency?EPA?.