Study On The Detection Of Trace Nitro-explosive By Halogen Ion Modified Coinage Nanoparticles

The environmental pollution are becoming more and more evident,under the circumstances of nitro-aromatic explosives in military and civil application is becoming wider and wider.Explosives will unavoidably be leaked in the process of production,manufacture and transportation.The residue explosive components in the soil and water are not only harmful to the environment,but also indirectly pose a threat to human life.In addition,explosives are also the most direct means for terrorism to endanger social stability and people’s safety.So we take the explosive detection as the focal point of anti-terrorism and the maintenance of stability.In recent years,Surface-Enhanced Raman Scattering(SERS)technique has become one of the most important spectroscopic methods for the detection of trace explosives because of its advantages of being portable,instant response and high sensitivity.Among them,the SERS substrate with ultra-high sensitivity is the prerequisite for the successful detection of trace explosives by SERS technology.Therefore,this paper has developed a simple,time-saving and low-cost method to prepare ultra-high sensitivity SERS substrate and realize the detection of nitro-type explosives.Firstly,in order to improve the sensitivity of SERS substrate,this paper chooses chemical reagent to modify nano-particles,and obtains SERS substrate with ultra-high sensitivity.In the experiment,the preparation method of SERS substrate was obtained by optimizing the types of nanoparticles,chemical reagents and preparation conditions.1 mL of Ag nanoparticles(the reducing agent was trisodium citrate)was concentrated by centrifugation to give about 5 μL of nanoparticles concentrated colloid,and then adding 25μL of KI solution(concentration of 10 mM)mixed evenly,in the dark conditions for 20 min,Ag IMNPs substrate was obtained.The results showed that Ag nanoparticles modified with iodide had good SERS activity,and the lowest detection concentration of 2,4-DNT and TNT was 0.1 nM.The detection limit of mass was about 0.364 pg and 0.454 pg,respectively.Then,the enhancement mechanism of Ag IMNPs substrate was discussed in this paper.The results showed that there were two reasons for the enhancement mechanism of Ag IMNPs.One is that in the UV-vis scanning of Ag NPs,KI modified Ag NPs will redistribute the maximum UV absorption wavelength,possibly because KI agglomerates Ag NPs,which can increase the SERS signal of explosives.The second is that KI scavenges the surface impurities of Ag NPs,giving more "vacancies" to the surface of nanoparticles,providing more opportunities for the contact of explosive molecules with nanoparticle surfaces.Under the combined influence of these two enhancement mechanisms,the sensitivity of Ag IMNPs was much higher than that of Ag NPs.And Ag IMNPs substrate has different degrees of enhancement effect on a variety of aromatic nirro-cornpaund,which indicates that Ag IMNPs substrate can be applied to the rapid detection of various nitro-type explosives.Thanks to the high sensitivity of the Ag IMNPs substrate,it can be used in conjunction with his materials to expand its use in environmental monitoring,security and food safety applications.