Construction And Application Of SERS Substrates Based On Hierarchical Nanostructure

In recent years,the application of surface-enhanced Raman scattering（SERS）technology based on hierarchical nanostructure in the detection of trace hazardous substances has attracted wide attention and research at home and abroad.Although many meaningful research results have been achieved in this field,there are still many problems to be solved.Therefore,in this paper,we aimed at these problems,designed and prepared a series of SERS base based on nano assemblies,and investigated its application in detection of trace antibiotics,pesticides and illegal food additives in water.Firstly,we prepared a kind of Ti mesh loaded with Ag“nanobosk”by electrodeposition method,and systematically studied its SERS effect on trace norfloxacin in water.This research mainly included the influence of the amount of Ag,the pH value of the solution,the type of ions in the water and the salinity on its SERS effect.On this basis,we also preliminarily explored the SERS enhanced mechanism of this substrate.Secondly,a kind of TiO₂ nanotube arrays were fabricated on Ti meshes via anodic oxidation and decorated with Ag nanoparticles by a photodeposition process.Subsequently,we studied in detail its SERS effect and enhanced mechanism on trace thiram in water.On the basis of the above research,we built a prototype SERS sensor and applied it to the detection of trace amount of fumethane in actual water.Finally,we used hydrothermal technology to construct a sieving nanostructure stacked by MoS₂ nanosheet on Ti sheet,and loaded Ag nanoparticles on it to prepare Ag nanoparticles/MoS₂ hierarchical nanostructure.Subsequently,the SERS effect of the hierarchical nanostructure on trace malachite green in water and its influencing factors were investigated.On this basis,we construct a prototype sensor which can be used in the flow system and apply it to the detection of trace malachite green in the flow system.Through research,we obtained the following results:1.Ti mesh loaded with Ag“nanobosk”had ultra-sensitive SERS response to norfloxacin.When the concentration of norfloxacin was 1×10^-5 mol L^-1,the enhancement factor at 1389cm^-1 could reach 5.1×10³.Under the optimal conditions,the detection limit of norfloxacin can reach 1×10^-10 mol L^-1.Our work provides a new strategy for the design of a highly sensitive sensor platform for the routine detection of norfloxacin in water.2.TiO₂ nanotube array modified with Ag nanoparticles loaded on Ti mesh is a kind of ultra-sensitive SERS substrate which can be used to detect trace thiram in water.The detection limits can reach 1×10^-9 mol L^-1 and 1×10^-7 mol L^-1 in deionized water and tap water,respectively.In addition,the SERS signal obtained on this substrate has remarkable reproducibility[relative standard deviation<6%（spot-to-spot）],excellent reproducibility[relative standard deviation<6%（spot-to-spot）],high selectivity and good stability.This study indicated that the SERS substrate had great application potential in the detection of trace amount of SERS in drinking water.3.The MoS₂ sieve hierarchical nanostructure modified by Ag nanoparticles loaded on Ti sheets has satisfactory detection ability in direct detection of trace malachite green SERS signal in aqueous solution,and its detection limit can reach 1×10^-8 mol L^-1.In addition,this substrate can not only be used to directly detect malachite green in the solution,but also can be applied in the flowing water system.The detection signal provided is very stable.This SERS substrate,which can be used in the mobile water system,has great application potential for online detection of trace malachite green in water.