Study On The Preparation Of Cu₂O SERS Material And Application In Detection Of Sudan Red

Surface-enhanced Raman scattering（SERS）is a promising analytical technique for the identification of tracing chemicals.Compared with traditional precious metal substrates,semiconductor substrates have significant advantages such as high selectivity,low cost,high reproducibility and high stability.However,most previous studies were limited to specific probe molecules（e.g.rhodamine 6G[R6G]）,and practical applications are still relatively few.Therefore,a major challenge in this field is to make it practical.Sudan red is a common industrial dye,but it cannot be used in food because of its carcinogenicity.However,many illegal vendors still add it to food or traditional Chinese medicine to maintain the bright luster of the product.The current method for detecting Sudan red is mainly chromatography,but the process is often complicated and time-consuming.Thus,a simple,effective and highly sensitive detection way is needed.In this paper,a series of morphological structure and chemical composition adjustments and optimizations were carried out about semiconductor SERS material cuprous oxide,using Sudan Red 3 as a probe molecule,practical detection simulations were carried out,finally a simple and effective SERS detection method was established.1.Based on the cubic structure of cuprous oxide,the morphology and valence had been optimized through ascorbic acid corrosion,oxidation,reduction and hydrogen thermal reduction.Finally,a cuprous oxide cube with a rich oxygen defect surface was designed,which greatly enhanced the charge transfer between cuprous oxide and Sudan Red 3.In ethanol solution,SERS effect of Cu₂O substrate on Sudan Red 3 was better than that of precious metal gold.Silver and other substrates,limit of detection had reached 10^-6 mol/L.2.On the basis of the cubic structure of cuprous oxide,using the porous properties of organic framework,a thin layer of organic matter Trimesic acid（H₃BTC）was wrapped on the surface of the cube to successfully synthesize a new core-shell structure Cu₂O@BTC,which increased the diversity of cuprous oxide’s morphology and structure.Finally it can be beneficial to SERS detection by enriching probe molecules and reducing the detection limit by an order of magnitude.3.Using the optimized defective cuprous oxide substrate,the detection of Sudan Red 3in the simulated actual Chinese medicine system and multi-component pigment mixture system was successfully realized,and finally limit of detection had reached 0.3 mg/kg in wolfberry.It can meet the EU 2003/460/EC LC-UV quantitative standard of 0.5-1.0 mg/kg;synthesized a simple and effective SERS substrate,which can be used for the rapid detection of Sudan Red3,not only for the detection of Sudan Red in a practical system Provided solutions but also expand the application of semiconductor materials in actual scenarios.4.Through the investigation of the SERS interaction between Sudan Red 3 and cuprous oxide,it has been proved that the semiconductor cuprous oxide defect cube can realize the specific recognition of Sudan Red 3,which is derived from the charge transfer between the two.The oxygen-rich cuprous oxide surface provides effective binding sites for Sudan Red 3 dye molecules,and the modified cuprous oxide structure enhances the CT interaction between the substrate and the probe molecule.Research on the mechanism of SERS based on materials can contribute a lot to the further development of SERS technology.