Preparation Of Nobel Metal SERS Active Substrate By Porous Structure Films

Surface-enhanced Raman scattering has great potential in the dectection of tiny amount of small molecules since it was discovered as a unique spectrum detection technology.Therefore,it was gradually applied in many fields such as environmental monitoring,food safety,medical treatment and health,photoelectric sensor,and so on.It is well known that the preparation of an active substrate is a prerequisite for obtaining a SERS signal.In order to make the SERS technology apply to quantitative analysis better,the obtained SERS substrates should have advantages of strong enhancement,good uniformity,easy preparation and storage,convenience and so on.So,the preparation method of SERS active substrates is particularly significant.Up to now,the domestic and foreign researchers have been carried out a lot of work and made greater progress in the preparation of SERS active substrates and its SERS performance.But there still exists lack of low cost,uniform,stable,good repeatability and strong enhanced capability of universal SERS active substrates.Based on the current situation,Au,Au-Ag and Ag nanoparticles on honeycomb-patterned porous films were prepared and the SERS performance was systematically studied.The main results of this paper are as follows:?1?The polystyrene-block-poly?4-vinylpyridine??PS-b-P4VP?honeycomb porous structure films were prepared by static breath method.The effects of solvent,polymer concentration and molecular weight on the formation of honeycomb porous structure films were studied.The result shows that the optimum concentration of PS?122k?-b-P4VP?22k?solution for preparing well-organized honeycomb porous films is 30 mg/m L when trichloromethane?CHCl3?was used as the solvent,the pore diameter is about 2.87 ?m.Both high and low concentration would form irregular pore structure.When the block ratio of the block copolymers is 5:1,the ordered structure of the porous structure is the best.The regular porous film could be obtained at 10 mg/mL when carbon disulfide?CS2?is used as solvent for PS?122k?-b-P4VP?22k?,but the pore size is larger,it's 4.27 ?m,and with the concentration increases,pore structure gradually disappears.?2?The treated honeycomb-patterned porous structure film was used as template,and the Au nanoparticles films were prepared by combining the photochemical reduction method.Au nanoparticles film with best SERS performance was prepared by UV light-assisted reduction of Au precursor?0.025 mol/L HAuCl₄ solution?VH₂O:VCH₃CH₂OH=1:1??with 3 h.The enhancement factor for R6 G reaches 6.50×10⁶,the detection limit could be as low as 10^-8mol/L,the substrate also has a favourable SERS enhancement effectfor CV,its enhancement factor reaches 6.03×10⁴.?3?Au-Ag nanoparticles films were prepared by photochemical reduction using the Au nanoparticles thin films prepared as described above as templates.Au-Ag nanoparticles film with best SERS performance was prepared by UV light-assisted reduction of Ag precursor?0.05 mol/L AgNO₃ solution?VH₂O:VCH₃CH₂OH =1:1??with 2 h.The enhancement factor for R6 G reaches 1.05×10⁷,the detection limit could be as low as 10^-9 mol/L,the enhancement factor for CV reaches 2.41×10⁶.And the prepared substrate has good stability,the signals collected at 121 points over a 30 ?m × 30 ?m area give relative standard deviation lower than 20%.?4?The Ag nanoparticles array films were prepared by similar method.Ag nanoparticles film with best SERS performance was prepared by UV light-assisted reduction of Ag precursor?0.05 mol/L AgNO₃ solution?VH₂O:VCH₃CH₂OH =1:1??with 3 h.The enhancement factor for R6 G reaches 1.31×10⁹,the detection limit could be as low as 10^-10^mol/L.The enhancement factor for CV reaches 8.46×10⁵.Moreover,Ag nanoparticles array film has better stability when the R6 G adsorption way was soaking,the signals collected at121 points over a 30 ?m × 30 ?m area give relative standard deviation lower than 13%.