Fabrication Of Novel SERS Substrates And Its Application In The Detection Of PAHs And Small Sulfur-Containing Gas Molecules

In view of the fact that PAHs in water and harmful gases in the atmosphere have great harm to the environment and human health,there is an urgent need for new detection methods for rapid detection and identification of PAHs and harmful gases,which has practical needs and academic significance.In recent years,surface-enhanced Raman scattering(SERS)has exhibited rich characteristic fingerprint information through the plasmon resonance effect,and has become more widely used in biomedicine,environmental monitoring,food safety and other fields.At present,SERS technology is one of the main research hotspots of Raman analysis through the construction of new nanoprobes,enabling it to target and bind to target analytes with high sensitivity and high selectivity.In this thesis,two different types of composite materials are designed based on silver nanomaterials and two MOF materials,so as to apply them in the analysis and detection of polycyclic aromatic hydrocarbons and harmful gases.The main work is as follows:(1)In-situ synthesis of core-shell HKUST-1(Cu)@Ag for ultra-sensitive SERS detection of polycyclic aromatic hydrocarbons.In this chapter,a simple method for manufacturing SERS active chips by in-situ electrodeposition to integrate core-shell HKUST-1(Cu)@Ag NP onto a screen-printed electrode(SPE)is explored.HKUST-1(Cu)@Ag nanocomposite combines the rich Raman "hot spots" of high-density Ag NP and the excellent adsorption performance of MOF,which can effectively enrich analytes near these "hot spots" and improve the measured value of sensitivity SERS.The core-shell structure of HKUST-1@Ag is controlled by Cu(NO3)2/AgNO3 aqueous system,and experimental variables such as electrodeposition time and potential are systematically studied.The optimized Ag NP-modified HKUST-1 polyhedrons are tightly clustered on the surface of the SPE chip and show high SERS activity to detect ATP at concentrations as low as 5×10-10 M.What's more,HKUST-1@Ag nanocomposite shows high stability,excellent repeatability and recyclability.In addition,the potential practical applications of SERS active chips were evaluated by detecting PAHs in environmental water samples.For PAHs,the method is effective over a wide concentration range(0.5 nM to 0.5 M)with a detection limit of hundreds of pM.This research not only provides a new method for customizing MOF-based SERS substrates,but also offers great practical potential for field screening or field care applications.(2)Preparation of fluorescent-SERS dual-probe nanocomposite and its application in the selective and sensitive detection of hydrogen sulfide and sulfur dioxide.In this chapter,the fluorescent-SERS dual-probe nanocomposite,Ag@MOF-5-NH2 core-shell nanocomposite,was successfully prepared by wrapping silver nanoparticles in an organometallic frame material by solvent method,which can be controlled by controlling the amount of silver nanoparticles.Sensitive performance of Ag@MOF-5-NH2 core-shell nanocomposite in SERS detection.Due to the porosity and large specific surface area of the organometallic frame material,the hydrogen sulfide gas can be better enriched on the surface of the silver nanoparticles to improve the sensitivity of SERS detection.We further investigated its sensing characteristics for SO2 gas and its derivatives as luminescent probes.The results show that the Ag@MOF-5-NH2 probe can detect SO2 derivatives(i.e.,SO32-)in real time selectively and sensitively for 15 seconds in real time with a lower limit of 0.168 ppm and a response time of less than 0.16 ppm through the light-on effect.It is important that the light-on phenomenon can be observed with the naked eye.In addition,Ag@MOF-5-NH2 also shows good anti-interference ability,strong luminous stability and reusability,which means that this material is an excellent sensing candidate.Ag@MOF-5-NH2 core-shell nanocomposite materials,which can detect silver and MOF-5-NH2 nano-organic metal frame materials that can detect two harmful gases separately,have greatly improved the portability of gas detection.The nanocomposite materials can provide a strategy for future multi-gas detection.