Preparation Of SERS Substrate Based On Silver Nanoparticles And Its Application In TNT Trace Detection

The improper disposal and application of 2,4,6-trinitrotoluene（TNT）will threaten citizens’personal safety,disturb social order and affect environmental quality.In terms of environmental pollution,because TNT is difficult to degrade,it can penetrate into the soil and water system,participate in the ecological cycle for a long time,and even produce"pink water".It is difficult and expensive to clean up.Therefore,detecting traces of TNT in advance or finding hidden TNT is of great significance to the country,personnel,and the environment.As a detection technology with high sensitivity and good selectivity,the surface-enhanced Raman scattering（SERS）technology has shown great potential in TNT trace detection and has attracted widespread attention.The construction of active SERS substrate is the key to this technology.In this paper,Ag nanoparticles-based SERS substrates were prepared,which showed excellent sensitivity and selectivity.The main research contents are as follows:（1）The Ag nanoparticles were plated on the surface of silicon wafers through redox reaction.By exploring the influence of HF concentration,Ag NO₃ concentration,reaction time and temperature on the distribution morphology of Ag particles,the reaction conditions were screened out,under which Ag particles on the surface of silicon wafers were uniformly distributed and the gap between the particles was small.When reacting at room temperature for60s in the 4.8M HF/0.005M Ag NO₃ solution,the Ag particles on the surface of the silicon wafer were relatively evenly distributed with small gaps,which was conducive to the near-field coupling effect,resulting in the enhancement of local electromagnetic fields and the formation of"hot spots".（2）The Raman spectrometer was used to test the sensitivity of the p-aminothiophenol（4-ATP）molecule-modified SERS substrate.Through the Meisenheimer complex formed between4-ATP and TNT molecules,the Raman signal can be greatly enhanced,so as to indirectly realize the trace detection of TNT.The detection limit of SERS substrate was as low as 10^-13M.In addition,the interaction between 4-ATP and TNT,that is,the selectivity of the SERS substrate,was verified by ultraviolet-visible absorption spectroscopy.（3）Based on the excellent localized surface plasmon resonance（LSPR）effect of noble metal Ag nanoparticles,4-ATP modified Ag NPs were introduced to prepare Si-Ag@4-ATP@TNT@4-ATP@Ag NPs.After testing the samples with the Raman spectrometer,it was found that the sensitivity of SERS substrate had been further improved,and TNT with the concentration as low as 10^-17M could be detected.In addition,compared with Si-Ag@4-ATP@TNT,this sample showed better uniformity.