Preparation And Properties Of Silver Nanoparticals On Silicon And TiO₂ Film For SERS Substrate

Silver nanoparticals on silicon and TiO₂ films for SERS substrate were prepared by using liquid phase reduction method and photo catalytic reduction method.The properties of uniformity and sensitivity of the substrates were investigated.The SERS of R6G on the substrates were studied.1.Preparation of silver nanoparticals SERS substrate on silicon by using liquid phase reduction method.Silver nanoparticals sol was prepared by liquid phase reduction method with AgNO₃ as the precursor,ascorbic acid as reductant,polyvinylpyrrolidone?PVP?as surfactant.Deposited silver nanoparticals sol on silicon wafer substrate to get the silver nanoparticals SERS substrate.The optimal SERS substrate preparation conditions were investigated.The effects of ascorbic acid and PVP volume on SERS substrate properties was studied.The experimental results showed that:0.2mL AgNO₃ solution?1mol/L?,2mL PVP?1%?and 1mL ascorbic acid?0.1mol/L?were added into 10m L of deionized water in a beaker with stirring,the silver nanoparticles grows better.The SERS effect of the silver nanoparticals substrate were tested with R6G,enhancement coefficient was upto 5.59×10⁸.The uniformity and sensitivity of the substrate were studied.The results showed that the maximum standard deviation of the characteristic peak intensity was 5.64%,and the limit of detection to R6G was 10^-8mol/L.2.Preparation of silver nanoparticals SERS substrate on TiO₂ films by using photo catalytic reduction method.TiO₂ films was obtained by sol-gel method with chemical pure tetra-butyl titanate,chemically pure acetylacetone,nitrate as raw materials.Also using reduction method to plate a layer of silver nanoparticles on TiO₂ film by UV light to get the silver nanoparticals SERS substrate.Experimental focused on the effects of factors like the pulling speed of tiras machine,the calcination temperature and time of muffle furnace,the time of lamp irradiation samples vertically with 254nm UV in black box on the photo catalytic activity of Raman enhancement.The experimental results showed that:the pulling speed was 200mm/min,the calcination temperature of muffle furnace was 520?,calcination time was 60min,UV light vertical irradiation time was 90min,the silver nanoparticles grows better.The SERS effect of the silver nanoparticals substrate were tested with R6G,enhancement coefficient was upto 6.49×10⁸.The uniformity and sensitivity of the substrate were studied.The results showed that the maximum standard deviation of the characteristic peak intensity was 7.24%,and the limit of detection to R6G was 10^-8mol/L.3.Preparation of silver nanoparticals SERS substrate on TiO₂ films by using liquid phase reduction method.According to the previous study,Ti O₂ films was obtained by sol-gel method and silver nanoparticals sol was prepared by liquid phase reduction.Deposited silver nanoparticals sol on TiO₂ film substrate to get the silver nanoparticals SERS substrate.The uniformity and sensitivity of the substrate were studied.The results showed that the maximum standard deviation of the characteristic peak intensity was7.62%,and the limit of detection to R6G was 10^-9mol/L.It's better than which were prepared on TiO₂ films by using photo catalytic reduction method and on silicon by using liquid phase reduction method.4.Pesticide dimethoate detection by using the silver nanoparticals SERS substrate.Raman test of dimethoate pesticide using the highest sensitivity of SERS substrate which was obtained in the research.With the study on the qualitative analysis of Raman spectra and the analysis of pesticide dimethoate concentration,the results show that the characteristic peaks of SERS spectra of dimethoate mainly occurred in the 611cm^-1?761cm^-1?901cm^-1?1040cm^-1?1317cm^-1?1446cm^-1?1659cm^-1,the 761cm^-1?901cm^-1?1317cm^-1?1446cm^-11 peak intensity around the most obvious,with the increase of the concentration of dimethoate,characteristic peak intensity increases gradually,showed a linear correlation,the linear correlation coefficient reached to 0.99593.Through the comparison and analysis,the concentrations of dimethoate can be estimated through the characteristic Raman intensity at 1446cm^-1when the concentration of pesticide dimethoate in 2mg/L¹0mg/L.