Preparation Of Nano-iron Oxide Nanocomposites And SERS Properties

At present,Surface Enhanced Raman Scattering?SERS?spectroscopy has become one of the most sensitive spectroscopic techniques in surface science.It has been widely used in many fields related to surface science,including biosensors,food safety and catalysis.Exploring the preparation and mechanism of SERS substrates is closely related to the effective broadening of SERS applications.In recent years,with the rapid development of nanotechnology,the controllability of the synthesis of SERS substrate materials has become possible,which not only improves the enhancement effect,but also improves the detection sensitivity.Nevertheless,there are still many things that can be studied about SERS basement.Especially,the selection and preparation of SERS substrates are particularly important in the study of SERS substrates.Based on this,the preparation conditions of iron matrix composites were explored in this paper,in order to prepare nanoporous iron oxide and elemental iron.Silver nanoparticles were loaded on the surface of nanoporous iron oxide by thermal decomposition method;gold and silver nanoparticles with different sizes were prepared by reduction method,and assembled onto iron by self-assembly method;their SERS properties were tested,and the mechanism of SERS was analyzed.The main research work is summarized as follows.Surface Enhanced Raman Scattering Spectroscopy?SERS?,as a highly sensitive detection and analysis technology,has a variety of active substrates.Among them,one of the most concerned active substrates for SERS is the composite of semiconductor and Nano-noble metal particles,which shows good SERS performance as SERS substrates.In this paper,an n-type semiconductor porous nano-Fe₂O₃/nano-silver composite was selected as SERS substrate.FeCl₃·6H₂O hexahydrate,PVP of polyethylene pyrrolidone,CH₃COONa·3H₂O of sodium acetate trihydrate,formamide and ethanol were used as solvents to prepare nano-porous iron oxide by hydrothermal method.The solvent formamide used in the preparation of iron oxide has pore-forming effect and can produce pore channels during the roasting of iron oxide.Because the pore channels on the surface of Fe₂O₃ have good mass transfer and absorption.These porous materials are widely used in nanocomposites to construct SERS active substrates.Silver nanoparticles were synthesized by hydrothermal decomposition using porous?-Fe₂O₃ as solid phase carrier.Rhodamine R6G was selected as probe molecule and its SERS properties were characterized.The optimal load of Ag nanoparticles was 6.5%by adjusting the load of Ag nanoparticles and investigating its influence on SERS performance.The results showed that a nanocomposite SERS substrate with both adsorption and detection effects was obtained.The nanoporous iron oxide synthesized by the above method was calcined at high temperature and reduced to elementary iron.Gold and silver nanoparticles were loaded on the surface of elementary iron.R6G,PATP,Thiram and melamine were selected as probe molecules for SERS measurement.The results of SERS test show that the optimal size,shape and spatial distribution of gold and silver nanoparticles are explored to optimize the SERS substrate.In this paper,the pre-synthesized?-Fe₂O₃ was calcined and reduced to elementary Fe.Because of the existence of porous structure on the surface of iron oxide,there are also porous channels on the surface of elementary Fe.After that,the SERS performance of the elementary Fe was tested.By changing the size of Au/Ag nanoparticles and investigating the influence of different sizes on SERS performance,it is concluded that Au/Ag nanoparticles have the best performance when the size of Au/Ag nanoparticles is 50 nm.After Au/Ag nanoparticles were compounded with Fe,the target molecule was adsorbed,separated and detected.This method provides a new idea for the preparation of functional SERS substrates.