Multifunctional SERS Substrates:Preparation And Application In Several Environmental Pollutants Detection

As a powerful spectral analysis technique,surface-enhanced Raman spectroscopy (SERS) has been widely used in analytical science,environmental analysis and food safety due to its unique properties such as high-sensitivity,finger-print specificity,fast and nondestructive detection.However,there are still some challenges should be overcome in the application of SERS,including sensitivity,reproductivity,repeatability,long-term stability and multifunctionality.To solve these problems,we prepared three different kinds of SERS substrates to improve the performance of SERS sensors in the detection of multiple environmental pollutes,such as organic dyes and pesticide residues.1st work: Au nanocone arrays were directly grown on Ni foam (AuNCA@Ni foam) by the replacement reaction between Ni foam and HAu Cl4 in the presence of CTAB.The self-supporting,stable,flexible and portable AuNCA@Ni foam could be employed as high-performance SERS substrate for the containing 3D macroporous structure and abundant sharp tips of Au nanocone arrays can generate a considerable number of “hot spots” to magnify SERS signals and improve sensitivity.Employed CV and NB as probe molecules,the limit of detection (LOD) of CV and NB in standard solutions are 0.03 n M and 0.5 n M,respectively,and the LODs of CV and NB in real samples are 3 n M and 5 n M,respectively.The facile prepared,cost effective,stable,sensitive substrate possesses great values in the environmental monitoring.2nd work: Layer-by-layer self-assemble technique was used to prepare MIL-100(Fe)metal-organic frameworks encapsulated Au nanoparticles decorated magnetic Fe3O4 nanoparticles [Fe3O4-Au@MIL-100(Fe)] substrate for the detection of environmental pollutes and pesticide residues.Magnetic core can realize rapid separation and concentration,avoid tedious centrifugation;the interlayer Au nanoparticles with dense and uniform distribution can improve SERS sensitivity and reproductivity;the outer MIL-100(Fe)metal-organic frameworks shell with large surface area can absorb a considerable number of target molecules and introduce additional chemical enhancement.For the detection of MG and thiram real sample,the Fe3O4-Au@MIL-100(Fe) exhibited excellent sensitivity with LOD of MG andthiram down to 4.4 n M and 15 n M,respectively.Moreover,the substrate also exhibited good reproductivity with RSD of MG and thiram less than 13% and 6% on ten random points.Besides,the substrates also can realize quantitative analysis of MG and thiram,recycling detection.Such a multifunctional and high-effective SERS substrate has broad application prospects on environmental monitoring and food safety analysis.3rd work: We prepared novel multifunctional Au nanoparticles decorated MNPs-MoS2 microflowers composites (MNPs-MoS2@Au) for SERS detection and photocatalytic degradation of organic dyes.MNPs were prepared by hydrothermal method,then MoS2 microflowers were grown around MNPs by solvothermal method,and finally Au nanoparticles were uniformly decorated onto MoS2 under stirring.The composite integrated magnetic concentration,the large surface area of MoS2,and the uniform distribution of Au nanoparticles,exhibited excellent properties in SERS detection of organic dyes.The LODs of CV,MG and MB are 1 p M,0.15 n M and 1n M,respectively.The substrates also exhibited good reproductivity with RSDs less than 6% and 11% of CV and MG on 10 random points.Furthermore,the composite could be used as photocatalyst for photocatalytic degradation of organic dyes,the decolorization of RhB is over 90% in 40 min.Such a facile prepared,novel and multifunctional material could be applied in SERS analysis,environmental detection and restoration.