Fabrication of Reproducible SERS Substrate at Toluene/Water Interface

The Au@SiO2 core-shell nanoparticles with a shell thickness of 4 nm were prepared by the hydro-lysis of sodium silicate in boiling water.A novel method for the assembly of Au@SiO2 nanoparticles film at a toluene-water interface was developed to prepare a close-packed monolayer film.The film was transferred onto a Si substrate.As a comparison,Au@SiO2 nanoparticles were chemically attached onto ITO substrate.The surface enhanced Raman scattering(SERS) activities and reproducibility of the above two kinds of film substrate were investigated using 1,4-dithiophenol(1,4-BDT) as probe.The results revealed that the shell of SiO2 avoided direct contact between the probe and the substrate.The adsorbed probe molecules could be removed by the immersion of the substrate into NaBH4 solution.The Au@SiO2/ITO substrate exhibited poor reproducibility and the SERS activity decreased with the increase of the washing times,while the compact film on Si substrate fabricated from the water-toluene interface showed high stability and reproducibility for the SERS effect.The Au@SiO2 film formed on the double phases interface could be used as a reproducible SERS substrate.