Forming Mechanism And Raman Enhancement Properties Of Graphene/Carbon Cloth/Silver Composite Structure

Surface-enhanced Raman scattering(SERS)is an advanced trace molecular spectroscopy detection technique,which can effectively solve the problem of weak signal in the traditional Raman detection process.In recent years,with the rapid development of spectroscopy technology and micro-nano materials,SERS technology has been rapidly developed and has been widely used in the detection of micro-trace substances of food safety,drug safety,and environmental safety.However,SERS technique still has some problems.For example,the unclear nanostructure forming mechanism leads to poor uniformity of the SERS substrate,which causes the Raman detection signal to fluctuate;the sensitivity of SERS substrates with uniform morphology needs to be enhanced;and most SERS substrates have poor detection capabilities for complex surfaces,which limits the application range of SERS technique.(1)The forming process of silver nanoparticles(AgNPs)was explored by vacuum thermal evaporation and high temperature annealing.By depositing silver films with different thicknesses,the influence of different thickness parameters on the dewetting process of metal films under the same annealing conditions was studied.Scanning electron microscope(SEM)and atomic force microscope(AFM)were used to characterize the morphology of the SERS substrate.And according to the metal nanoparticle formation model,the reasons why the thickness parameter affects the morphology of the SERS substrate were analyzed.Meanwhile,the finite difference time domain(FDTD)algorithm was used to study the electric field distribution of the SERS substrate.The principle and advantages of preparing SERS substrates by vacuum thermal evaporation and high temperature annealing methods were further elaborated.(2)The preparation and characterization(SEM/AFM/Raman)of graphene(GE)and silver nanoparticle composite structure(GE-AgNPs)structures were studied.Firstly,the electric field distribution of the GE-AgNPs substrate was studied through the multiphysics simulation software COMSOL Multiphysics,and it was found that graphene can effectively improve the performance of the substrate.Secondly,according to the morphological characterization results,the principle of graphene hindering the dewetting of the SERS substrate metal film during the high-temperature annealing process was theoretically analyzed.Finally,the influence of silver nanoparticles with different morphologies on the Raman spectra of graphene was analyzed,and the Raman detection ability of GE-AgNPs substrate was studied using the probe molecule rhodamine 6G(R6G).(3)The preparation of flexible carbon fiber cloth substrate decorated by Agnanoparticles(AgNPs-CFC)was studied.Firstly,the morphology of the substrate was characterized by SEM,and the influence of the three-dimensional flexible substrate on the deposition process of the metal film and the influence of different thickness parameters on the dewetting process of the metal film on the carbon fiber cloth were studied.Secondly,the structure of the AgNPs-CFC substrate was simulated by simulation software.And the influence of the size,morphology and position of the nanoparticles on the electric field distribution of the SERS substrate was analyzed.Finally,rhodamine 6G and crystal violet(CV)were used as probe molecules to study the sensitivity,stability and uniformity of the substrate.The research results show that the AgNPs-CFC substrate has excellent Raman detection ability.Moreover,the preparation process of this substrate is simple and the cost is low,which provides a new research idea for the preparation of large-area flexible SERS substrates.