Preparation Of Noble Metal Hydrothermal Carbon Matrix Composites For Surface-enhanced Raman Scattering

The purpose of this study is to explore the preparation of highly noble metal hydrothermal carbon-based composites and to study their performance in SERS.The content mainly includes the following parts:(1)Using glucose as carbon source,trihydrate and copper nitrate as copper source,sodium dodecyl sulfate(SDS),trioctylamine(TOA)and sodium citrate as surfactant,different structure Cu/C composites were prepared by hydrothermal carbonization.Crystallization of Cu in the composite was analyzed by X-ray powder diffraction(XRD).The composition and degree of graphitization of the hydrothermal carbon were analyzed by Raman spectroscopy.The morphologies and structures of Cu/C composites were observed by scanning electron microscopy(SEM)and transmission microscopy(TEM)images.The embedded copper-carbon composites are suitable for the synthesis of performance in SERS was tested using Rhodamine 6G(R6G)and crystal violet(CV)molecules.The detection limit of CV and R6G molecules up to 10-5M.(2)Using glucose as carbon source,chloroauric acid as gold source,SDS and TOA as surfactant,different structure Au/C composites were prepared by hydrothermal carbonization.The functional groups was analyzed by FT-IR.The composition and degree of graphitization in the composite were analyzed by Raman spectroscopy.The crystal structure of Au in the composite was analyzed by XRD.The morphology and structure of different composites were observed by SEM and TEM.The Au@C core-shell nanocomposites show a great increase of Raman signals for adsorbed probe molecules.The detection limit of CV and R6G molecules up to 10-8M.(3)Here,core-shell silver-carbon nanocomposites(Ag@CSs)were obtained using glucose as carbon source and stabilizer,silver nitrate as silver source,and TOA as soft template and extractant.It is worth mentioning that the shape of the silver core shows the hexagon shape,and we consider that TOA and glucose selectively adsorb the Ag(111)crystal face resulting in this growth pattern of the silver core.The hydrothermal carbon shell not only effectively avoids the agglomeration of Ag nanoparticles core,but also serves as a protective layer of the SERS active nanostructure during the whole course of the experiment.In addition,the thickness of the loose shell was significantly reduced after the product was stored in ethanol solution for a period of time.The detection limit of CV and R6G molecules up to 10-9M.It is found that dropped cast probe molecules onto Ag@CSs have a lower SERS activity,while that immersed in the probe molecular solution for a period of time have a higher SERS activity,indicating that the detection of the probe molecules using this Ag@CSs substrate may require an interactive process.