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[Display omitted] • New Mo1-xWxS2 two-dimensional nanosheets were prepared by the one-pot method. • Compared with MoS2, the Raman intensity of Rhodamine 6G (10−6 M) was amplified by 1.7 times with Mo1-xWxS2 nanosheets as the substrate. • With abundant edge active sites that facilitate charge transfer, Mo1-xWxS2 nanosheets could better enhance SERS signals. A new Mo 1- x W x S 2 two-dimensional nanosheets were prepared by the one-pot method. After certain Mo atoms in MoS 2 were replaced by W ones in a hydrothermal reduction procedure, Mo 1- x W x S 2 was formed on the Mo foil. Well enhanced Mo 1- x W x S 2 nanosheets were prepared when the sodium tungstate concentration got under control. Various characterizations were carried out, which indicate that Mo 1- x W x S 2 nanosheets with good crystallinity. Compared with MoS 2 , the Raman intensity of Rhodamine 6G (10−6 M) was amplified by 1.7 times with Mo 1- x W x S 2 nanosheets as the substrate. The characteristic Raman peaks could still be clearly distinguished until the concentration of Rhodamine 6G (R6G), Methylene blue (MB) and Crystal violet (CV) down to 10−8, 10−8 and 10−7 M, respectively. With abundant edge active sites that facilitate charge transfer, Mo 1- x W x S 2 nanosheets could better enhance SERS signals of target detection molecules and get a good linear relationship exists within the concentration and Raman peak strength. In addition, R6G SERS detection also shows excellent reproducibility and long-term stability of this TMDs SERS substrate. [ABSTRACT FROM AUTHOR]

A method for surface-enhanced Raman spectroscopy (SERS) sensing of polycyclic aromatic hydrocarbons (PAHs) is reported. Gold nanoparticles (AuNPs) decorated hydrophobic porous glycidyl methacrylate–ethylene dimethacrylate (GMA–EDMA) polymer is developed as the SERS substrate. GMA–EDMA material with porosity and permeability shows rapid and efficient adsorption of PAHs through presumed hydrophobic interaction, which brings the analytes close to the substrate. Meanwhile, the three dimensional porous morphology might benefit AuNPs distribution for high SERS enhancement. Studies on the effects of AuNPs surface coverage on the substrate and time of PAHs–substrate interaction are presented. The qualitative analysis and quantitative tendency of this method for PAHs detection are investigated with anthracene, phenanthrene and pyrene as probe molecules, showing that the characteristic fingerprint vibrational peaks of each PAH can be readily identified, and the limit of detections are 0.93 × 10 −7 , 4.5 × 10 −7 and 1.1 × 10 −7 M respectively. Moreover, the substrate exhibits high reproducibility with the relative standard deviation about 16% in spot and spot SERS intensity. Using this method for rapid screening of PAHs mixture in some water samples are performed well, which might be useful for environmental pollutions monitoring. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple method to remove PVP for high performance and reusable SERS substrate. • Cleaned AgNPs interface effectively enhanced the plasma resonance of the local surface (LSPR). • Residual PVP has basically no influence on detection of the molecular which absorbed stronger than PVP. The silver nanoparticles have been frequently used in SERS detection, for their unique optical properties and sensitive surface Raman enhancement properties. However, as the preparation of silver nanoparticles will use polyvinylpyrrolidone (PVP) to achieve the effect of reducing agent and surfactant, the surface of the prepared silver nanoparticles will be wrapped by PVP, forming an insulating layer and an ill-defined AgNPs interface, which limits the plasmonic coupling between the laminates of AgNPs. This paper reported a simple method to remove PVP for high performance and reusable SERS substrate, and the residue of PVP was studied after clean centrifugal by ethanol or water. When the number of cleaning times reached 10, there was basically no residual of PVP. The cleaned AgNPs interface effectively enhanced the plasma resonance of the local surface (LSPR) and greatly improved the SERS activity of the substrate. Moreover, probe molecules (R6G) are introduced to study the influence of single molecule PVP on subsequent detection. Through the competitive relationship between the two, it can be concluded that residual PVP has basically no influence on detection of the molecular which absorbed stronger than PVP, and the remaining PVP can be ignored. [ABSTRACT FROM AUTHOR]

• AgNPs/MIL-101(Fe) nanocomposites is used as a Raman enhanced substrate to detect R6G. The results show that the substrate has better stability and uniformity. Its R6G Raman assignment peak position RSD = 7.55%, enhancement factor EF = 2.09 × 109. • AgNPs/MIL-101(Fe) nanocomposites as a Raman enhanced substrate can detect the lowest concentration of paraquat at 10−12 mol/L, and the Raman signal is relatively stable in different acid-base environments. Recently, in the research of Surface-enhanced Raman scattering (SERS) technology, it is found that the preparation of enhanced substrate is particularly important. In this work, the most commonly used methods were used to synthesize AgNPs and MIL-101(Fe), and AgNPs/MIL-101(Fe) nanocomposite was obtained through self-assembly of the two substances. Four different probe molecules were detected with the self-assembled substrate and compared with the results of same probe molecules with AgNPs and MIL-101(Fe) as SERS substrate separately, it was found that AgNPs/ MIL-101 (Fe) nanocomposites had a strong enhancing effect as SERS substrate. The Enhancement Factor (EF) value of 10−6 mol/L Rhodamine 6G (R6G) was calculated as 2.09 × 109, and the Raman intensities of the peak relative standard deviation (RSD) of R6G Raman attribution was calculated as 7.55%. The time stability of the material was studied and it was found that the reduced Raman signal and poor reproducibility were due to the AgNPs placement time. AgNPs/ MIL-101 (Fe) nanocomposites were used as SERS substrate to detect Paraquat with a minimum concentration of 10−12 mol/L. The signal values of Paraquat Raman detected at 10−6 mol/L in different pH environments were relatively stable. [ABSTRACT FROM AUTHOR]