Preparation Of Au Polyhedral Nano-Substrate And Its SERS Detection And Application Of Environmental Pollutants

Objective:As material living standards improve,people pay more attention to their health and pay much attention about food safety.Pesticide residues on fruits and vegetables have long been a problem for the public.In recent years,pesticide residues have been tested in some supermarkets and found that most fruits and vegetables have pesticide residues.Surface-enhanced Raman Scattering does not need to consider whether the analyte absorbs in the ultraviolet and visible light region,and it can also avoid the error caused by sample injection.In this experiment,different shapes of Au nanocubes,Au nanotetrahedrons,and Au nanospheres were synthesized by the seed growth method,and the Raman detection ability of different shapes of Au polyhedrons on pesticide residues was studied,and the detection ability was selected.On this basis,the best substrate for the rapid detection of malachite green,thiabendazole,thiram,hexachlorobenzene and other pesticide residues.Methods:First synthesize Au octahedron seeds by seed-mediated method,and then use CTAB as a template,add HAu Cl₄to the Au octahedron seed solution,and control the saturation of the solution by controlling the amount and number of times the Au precursor is added,and then the Au nanoparticles with different appearances are cubic,tetrahedron,and Au nanospheres.Subsequently,crystal violet was used as the probe molecule to investigate the sensitivity and repeatability of the three morphologies of Au nanoparticles,and the target to be tested was used as the detection object for further exploration,and the tension of the three morphologies of Au nanoparticles was compared.Then select the Au nanoparticles with the strongest Raman strength as the SERS base to detect malachite in the fish pond water,thiabendazole on the skin of green apples,thiram in the soil,hexachlorobenzene and other pesticide residues In order to explore the Raman strength and physical properties of nanoparticles with different morphologies,to achieve the largest SERS enhancement effect.Results:1.Use the seed growth method to synthesize octahedral Au seeds,and control the supersaturation of the colloidal solution by controlling the amount of Au precursors,thereby controlling the formation of Au polyhedrons with different surface energies.Using resume as the probe molecule,and milligrams and thiram as the test object,a series of characterization and investigation show that the Au nanocube as the SERS substrate has the strongest SERS effect.At the same time,FDTD was used to simulate the field strength,and the results also showed that the Au nanocube has the strongest electromagnetic field.Therefore,we choose the Au nanocube as the optimal substrate for pesticide residue detection in practical applications.2.The experimental results showed that the sensitivity of Au nanocube to CV could reach 10^-9M,and the repeatability is 12.67%.Then,the emphasis on the apple skin,the thiram in the soil,and the MG in the pond water were tested.The detection limit of residues can reach 10^-9M,which shows that the Au nanocube as a SERS substrate has strong application value and detection potential in pesticide residue detection.Conclusion:In this experiment,three Au nanospheres with different morphologies were generated by the seed-mediated method,and through a series of characterizations to compare their Raman strength,the SERS substrate with the strongest Raman signal was successfully screened,and based on this In the above,the SERS detection on the skin of fruits and vegetables and the actual living environment was realized,and the enhancement mechanism of the SERS enhancement of Au nanoparticles with different morphologies was studied and discussed,and the combination and application of theory and practice were realized.