Preparation Of Functional SERS Substrate And Its Application In Analysis And Testing

Surface enhanced Raman?SERS?is characterized by a large amount of information.The spectra contain a large amount of chemical information,which can reflect structural information,chemical composition and environmental information.It is simple operation,no complicated pretreatment,direct in-situ detection,convenient and fast detection.It has high sensitivity and can be used for trace component analysis or even single molecule detection by enhancing adsorption and forming hot spots.Traditional SERS substrates are metal nanosol,such as gold nanoparticles?AuNPs?and silver nanoparticles?AgNPs?.This common substrate has some problems in uniformity,stability,reproducibility and signal enhancement.Composite SERS substrates can make the substrates more perfect and even acquire other properties,and expand the new SERS substrates.In this work,three kinds of composite SERS substrates were prepared based on traditional substrates,which were combined with metal organic frameworks?MOF?and zinc oxide materials and used for SERS detection.In this work,three kinds of functional SERS substrates were prepared based on traditional substrates,which were combined with metal organic frameworks?MOF?and zinc oxide materials and used for SERS detection.Specific research contents are as follows:In chapter 2,Au@MIL-101?Fe?functional SERS substrates were prepared by composite AuNPs and MIL-101?Fe?.MIL-101?Fe?was prepared by hydrothermal method,then MIL-101?Fe?was impregnated with chloroauric acid at different concentrations,and AuNPs were grown in situ in MIL-101?Fe?with sodium citrate as reducing agent.The structure of the substrate was characterized by transmission electron microscopy?TEM?and scanning electron microscopy?SEM?.The results showed that gold nanoparticles?AuNPs?were embedded in MIL-101?Fe?.Rhodamine6G?R6G?was used as a probe to investigate the SERS activity of the substrate.The Raman signal was the strongest when the concentration of chloroauric acid was 0.025mol/L.The Au@MIL-101?Fe?composite SERS substrate was used for the detection of creatinine.The minimum detection concentration was 0.1?m,and there was a good linear relationship between 100?mol/L and 1?mol/L.In chapter 3,MOF has large specific surface area and porous structure.Surface functional groups can capture target molecules close to the electromagnetic enhancement region through hydrogen bonding,electrostatic and?-?interaction.In this chapter,the core-shell structure of Au@MIL-101 was formed by self-assembly of MIL-101 layer by layer outside AuNPs@IP₆,with MOF as the shell and gold nanoparticles as the core,and a new composite SERS substrate was prepared.This substrate has a great Raman enhancement effect.The substrates were characterized by ultraviolet-visible spectroscopy,X-ray diffraction and projection electron microscopy?TEM?.Rhodamine 6G was used as probe molecule to investigate the stability of the substrate and SERS enhancement effect.Finally,the-COOH group on the surface of MIL-101 shell can interact with the amino group of urotropine?-NH₂?and pull the molecule of urotropine into the"hot spot"region to enhance the signal.The SERS signals of different incubation time were also investigated.When incubation time was3 minutes,the signals entered a stable stage.Using the excellent properties of Au@MIL-101,a new core-shell nanostructure SERS substrate,the concentration of trace Urotropine in real samples can be directly determined to 1×10^-99 mol/L,and there is a good linear relationship between 1×10^-8 and 3.16×10^-66 mol/L.In chapter 4,Zinc oxide?ZnO?is a semiconductor material.Semiconductor is a better photocatalytic material because of its unique energy band structure,and noble metals have surface enhanced Raman spectroscopy.They are combined to form a composite SERS substrate.In this chapter,Ag@ZnO was first synthesized by hydrothermal method,and then the hollow Au@Ag@ZnO composite SERS substrates were prepared by adding chloroauric acid and reducing chloroauric acid with silver nanoparticles as reducing agent.The substrates were characterized by ultraviolet-visible spectroscopy,X-ray diffraction and projection electron microscopy?TEM?.The substrate has good sensitivity,can detect CV to 5×10^-1010 mol/L,and has good reproducibility.After five photodegradation,it still maintains good SERS performance.