Preparation Of Nano-Silver Modified Transition Metal Disulfide Nanocomposites And Study On Their SERS Activity

The preparation of surface enhanced Raman scattering（SERS）substrates is a hotspot for scientists.The goal that people have been pursuing is how to prepare substrate materials with high sensitivity,high stability,high reproducibility and simple preparation methods.Precious metal nanostructures are widely used SERS materials because they have localized surface plasmon resonance（LSPR）effect.Transition metal sulfide（WS₂,MoS₂）is a promising support material because it has unique adsorption capacity and fluorescence quenching effect,which can stabilize metal nanoparticles.Tungsten disulfide（WS₂）and molybdenum disulfide（MoS₂）as stable inorganic graphene analogs have potential applications in the fields of electronics,optoelectronics,SERS sensors and biomedical detection.This article mainly explores the preparation of nano-silver modified tungsten disulfide nanosheets and molybdenum disulfide nanoflowers,and systematically studies their properties.The main research contents and results are as follows:1.Tungsten disulfide nanosheets and molybdenum disulfide nanoflowers were successfully synthesized by a hydrothermal method.Microwave heating technology was used to grow silver nanoparticles（Ag NPs）in situ on tungsten disulfide nanosheets（WS₂ NS）and molybdenum disulfide nanoflowers（MoS₂ NF）.Using WS₂NS/Ag NPs and MoS₂ NF/Ag NPs as SERS substrates,the effects of the number of Ag NPs on the morphology of WS₂ NS/Ag NPs and MoS₂ NF/Ag NPs were studied.Using Rhodamine 6G（R6G）as a probe molecule,Raman detection was performed on different concentrations of crystal violet（CV）and malachite green（MG）to evaluate the SERS performance of composite substrates with different numbers of silver nanoparticles.The Raman signal measured by WS₂ NS and Ag NP with a mass ratio of 1:10 as the SERS substrate has been found to be the strongest.The Raman signal measured by MoS₂ NF and Ag NP with a mass ratio of 1:6 as the SERS substrate has been found to be the strongest.2.The SERS substrate of WS₂ NS/Ag NPs showed a certain SERS performance(EF_（R6G）=2.193×10⁸,EF_（CV）=3.263×10⁵).In the range of 10^-8 mol·L^-1-10^-4mol·L^-1,the natural logarithm of the Raman peak intensity of R6G has a linear relationship with the negative logarithm of R6G concentration.The expression of the linear equation is y=5.288-0.6293x,where R²=0.9953,and the limit of detection（LOD）is about 10^-8 mol·L^-1;In the range of 10^-6 mol·L^-1-10^-2 mol·L^-1,the natural logarithm of Raman peak intensity of CV is linearly related to the negative logarithm of CV concentration.The expression of the linear equation is y=4.3102-0.6262x,where R²=0.9809,and the LOD is about 10^-6 mol·L^-1.The substrate prepared by this method can be stored at 20°C for 80 days.3.The SERS substrate of MoS₂ NF/Ag NPs showed excellent SERS performance(EF_（R6G）=2.75×10¹⁴,EF_（MG）=1.46×10¹²).In the range of 10^-14mol·L^-1-10^-4 mol·L^-1,the natural logarithm of the Raman peak intensity of R6G is linearly related to the negative logarithm of R6G concentration.The expression of the linear equation is y=13.961-0.881x,where R²=0.9850,and the LOD is about 10^-15mol·L^-1;In the range of 10^-12 mol·L^-1-10^-2 mol·L^-1,the natural logarithm of Raman peak intensity of MG is linearly related to the negative logarithm of MG concentration.The expression of the linear equation is y=10.081-0.712x,where R²=0.9869,and the LOD is about 10^-14 mol·L^-1.The SERS substrate prepared by this method has a storage stability of about 112 days at 20°C.