Application And Study Of MoS₂-based Glass Fiber Filter Paper In Molecular Separation And SERS Detection

Surface-enhanced Raman scattering?SERS?is an ultrasensitive vibrational spectroscopic technique that is able to detect molecules on or near the surface of plasmonic nanostructures,with the mechanism of the long-range electromagnetic enhancement?EM?and short-range chemical enhancement?CE?.SERS,which integrates high levels of sensitivity with spectroscopic precision,has tremendous potential for chemical and bio-molecular sensing.Recent studies indicate that MoS₂ can be an ideal platform to support SERS activity because of its many advantages.First,MoS₂ can provide chemical enhancement and efficient adsorption for various target molecules;hence,the sensitivity of the substrate is enhanced.Second,MoS₂ has chemical stability and can be obtained at low temperatures;these features endow the substrate with a long lifetime and effectively reduce energy consumption.Third,the MoS₂ nanosheet exhibits high surface area that makes it a promising supporting material to stabilize metal nanoparticles and form hierarchical composites.Gold and silver nanoparticles are the most commonly used substrates for surface Raman enhancement testing,The localized surface plasmon resonance?LSPR?generated on metal nanostructures induces strong plasmon-exciton coupling,resulting in strong light–matter interaction,this greatly enhances the local electromagnetic field near the metal nanostructures,the areas with greatly enhanced EM field become hot spots for surface-enhanced Raman.In order to combining the advantages of nobel metal nanomaterials with high electromagnetic enhancement ability and MoS₂ with efficient adsorption,it is necessary to prepare the MoS₂-based nanocomposites as SERS substrate.However,identification of a targeted analyte in complex real-world samples may be challenging due to overlapping of spectral signatures from different analytes as well as interference by highly fluorescent molecules that may be present.Therefore,a combination of separation and SERS detection is necessary to detect multiple targets in practice.Therefore,the main research works in my thesis are as follows three aspects:?1?Glass fiber filter paper were used as substrates for the growth of MoS₂ by the thermal decomposition method due to their high temperature resistance.Chemical reduction between MoS₂ and HAuCl₄ realizes the deposition of dense AuNPs on the glass fiber and by optimizing the experimental conditions,the GF-MoS₂@AuNP substrate with uniform and high-density gold nanoparticles supported on the surface of the MoS₂ was obtained.?2?Rapid screening of mixed small molecules has been achieved by the method of paper chromatographic separation.Porous GF membranes are is constructed by numerous compacted fibers which can provide capillary effect,and ethanol as a mobile phase can quickly spread under the action of capillary tension.As CV and TB molecules have different distribution coefficients in alcohol and water,with the spread of alcohol,they move at different speeds on the fiber to achieve separation.Then,the separation of mixed molecules was proved by the method of colorimetric detection and Raman spectroscopy.In addition,using CV and TB as the probe molecule,shows that the GF-MoS₂@AuNP substrate with high sensitivity,repeatability and stability.?3?In order to improve the SERS performance of the substrate,we prepared the GF-MoS₂@AuNP@AgNP substrates,and the controllable separation and then preconcentration of the mixture are realized by using the electrostatic interactions between electrolyte and molecules,which can be used to sensitively detect the each designated molecule.Then,Raman spectroscopy of the separated molecules was performed to confirm the improvement of the SERS properties of the GF-MoS₂@AuNP@AgNP substrate.