Surface-Enhanced Raman Scattering Activities Of Low-Symmetry SiO₂/Ag Core-Shell Composite Nanostructures Using Silver Mirror Reaction

Nanometal materials have the unique physical and chemical properties due to surface effect, small size effect, and surface plasmon resonance are widely used in the catalyst, sensors, antibacterial, surface enhanced Raman scattering effect aspects.The current method of preparing SERS active substrate have:electrochemical reduction, chemical reduction, chemical etching, magnetron sputtering, vacuum thermal evaporation, and electron beam lithography and so on. The method of preparing SERS active substrate and the roughness of substrate have much effect on surface enhanced Raman scattering effect.An excellent SERS substrate, should be easy to be prepared, easy to use, with good repeatability, high enhancement activity. Silver mirror reaction is a simple, low cost, good reproducibility of chemical reduction method. Fan Ni using silver mirror reaction made repeatable and stable Raman basement, and the enhancement factor is 105. Wenqin Wang prepared by the reaction of silver mirror reaction made silver-polypyrrole composite nanostructures, and using 4-mercaptopyridine as a probe molecule to study its Raman activity, calculated enhancement factor of 105.Using self-assembled monolayer of silica as template, depositing silver film on the template using silver mirror reaction, then we can get the Low-Symmetry SiO2/Ag Core-Shell Composite Nanostructures. Low-Symmetry SiO2/Ag Core-Shell Composite Nanostructures were characterized By TEM, SEM, UV-Vis absorption spectra. Chosing Methylene Blue trihydrate as probe molecule, SERS activity of the core-shell composite nanoparticles were studied. the result shows low symmetry core-shell composite nanostructures SiO2/Ag has a strong SERS enhancement, reach 107. The result showed that Low-Symmetry SiO2/Ag Core-Shell Composite Nanostructures were good SERS active substrates, and can have an effection on chemical and biological detection.TEM results show that SiO2 nanoparticles were prepared with ball shape, narrow particle size distribution, single well dispersed; SEM photographs and UV-Vis transmission spectra show that the SiO2 microspheres self-assembled monolayer close-packed monolayer of basic two-dimensional array and have Photonic bandgap properties significantly; high-resolution SEM shows the surface of composite nanoparticles is rough, as does not entirely cover the cap structure; XRD results show that the deposition of silica nanoparticles of silver on the film has good crystallinity; UV- Vis-NIR absorption spectra show that the non-symmetry composite nanoparticles surface plasmon resonance peaks have significant tunability.