Fabrication,Functionalization And Environmental Application Of Ag@C Hybrid Nanomaterials As SERS Substrate

Surface Enhanced Raman Scattering(SERS)spectroscopy,as a fast response and high sensitivity analysis technology,has been widely used in many fields,such as environmental detection,materials science,catalysis,biomedicine and sensing.Constructing an ideal SERS substrate is one of the most critical part for SERS technology.At present,conventional nanoparticle substrates have some issues such as low sensitivity,poor reproducibility,and poor stability,hindering the application of the substrate in actual environment.In this paper,the surface modification method has been used to improve the sensitivity of the SERS substrate,and the SERS substrate with good performance can also be used for the detection of actual water samples.Also,the self-assembly method is used to prepare a two-dimensional substrate,which can solve the problem of poor Raman signal reproducibility at a certain extent.Carbon-coated silver(Ag@C)nanoparticles were prepared by a one-step hydrothermal synthesis method,and the surface of the nanoparticles was modified by chlorodimethyloctylsilane(C8)to obtain Ag@C@C8 nanoparticles.SEM images and TEM images show that Ag@C nanoparticles have been successfully prepared,and the results of energy spectrometer,X-ray photoelectron spectrometer and contact angle results show that C8 has been successfully modified on the surface of the nanoparticles.By optimizing SERS experimental parameters,including C8 content and reaction time,the combination of agglomeration effect and core-shell structure is beneficial to improve the sensitivity and stability of the substrate.Typical probe molecules,such as rhodamine 6G,crystal violet and malachite green was used to test the substrate performance.And malachite green in actual water samples can be detected with aforementioned SERS substrate.Then the stability of the SERS substrate was investigated with crystal violet as the probe molecule.The results show that the intensity deviations of different characteristic peaks within four weeks can maintain within 17.5%,and the measured Raman signal remain good,and there is no obvious downward trend.The problem of easy oxidation of Ag nanoparticles is solved by our strategy.Using polyamide(PA)film as a carrier,Ag@C nanoparticles are self-assembled on the surface of the film through electrostatic interaction,and a two-dimensional PAAg@C film substrate is obtained.The TEM images show the successful preparation of the nanoparticles.The SEM results show that the carbon-coated silver nanoparticles are uniformly loaded on the surface of the polyamide film substrate.The Zeta potential results show that the nanoparticles are assembled on the surface of the polyamide by electrostatic force.By controlling the p H of the system,the combination of the coreshell structure and the two-dimensional SERS substrate are beneficial to improve the stability and reproducibility of the substrate,so that it can be applied to complex actual water samples.Rhodamine 6G,crystal violet and malachite green were used to test the SERS enhancement effect and uniformity of the substrate.The results show that the Raman signal intensity deviation of the same substrate is kept within 9.49%,and the Raman signal of the probe molecule crystal violet has excellent reproducibility and good stability.