Research On Preparation Of Silver/Semiconductor Oxide SERS Substrates And Its Raman Spectroscopy Detection

Due to the rapid development of modern industry and agriculture,chemical hazards in environmental water（such as dyes,phenols,pesticides,etc.）are becoming increasingly serious.Although many organic wastes are very small amounts in water bodies,they can be very harmful to humans and other organisms.Surface-enhanced Raman scattering（SERS）is a highly sensitive and non-destructive trace detection technique that can be well applied to the detection of organic pollutants.Various SERS substrates with enhancement effects such as precious metal gold and silver,semiconductors and their composite structures have been widely studied.The recycling of SERS substrates can also be achieved by the photocatalytic properties of some semiconductor oxides themselves.Based on Ag/semiconductor oxide composite structure SERS substrates,this thesis investigates the sensitivity,time as well as light stability and recycling effect of Ag/semiconductor oxide composite structure SERS substrates.The specific research work is summarized as follows:（1）The SERS performance and photostability of silver/graphene oxide SERS composite substrates were investigated.Ag microspheres of large size（around 50μm）were prepared by a simple one-step method using ascorbic acid as a reducing agent to reduce Ag NO3.Graphene oxide（GO）was prepared by the Hummers method,and the Ag/GO SERS composite substrate was formed by spin-coating GO solution on Ag microspheres for SERS detection.The detection limits of the prepared SERS substrates were as low as 10^-12 M for rhodamine 6G（R6G）,and the linearity of the detection results was significantly corrected by using the intrinsic characteristic peak of GO as an internal standard（IS）.And a stable detection of 30 days was achieved.In order to investigate the protection mechanism of GO on Ag in depth,the effect of xenon lamp simulated daylight irradiation on Ag substrate and Ag/GO SERS performance was studied comparatively for the first time.And a stable detection of 30 days was achieved.In order to investigate the protection mechanism of GO on Ag in depth,the effect of xenon lamp simulated daylight irradiation on Ag substrate and Ag/GO SERS performance was studied comparatively for the first time.（2）The SERS performance and SERS recycling performance of silver/graphene oxide/molybdenum oxide SERS composite substrates were investigated.Ag nanoparticles were generated in situ on the silicon wafer and spin-coated with GO solution and molybdenum oxide（Mo O₃）solution in turn.Mo O₃ was prepared by hydrothermal method.The adsorption of rhodamine 6G（R6G）with Ag/GO/Mo O₃ composite structure as SERS substrate also showed high sensitivity.A 150 W xenon lamp was used as the photocatalytic light source,and the SERS spectra were recorded for 2 min each time.Finally,after 40 min of light,the signal of MB on the substrate disappeared and the substrate was self-cleaned.The substrates were rinsed with deionized water to re-adsorb MB and the Raman test was repeated.Finally,the Ag/GO/Mo O₃ composite structured SERS substrate was achieved with 3 cycles of detection.