Interfacial effect of dual ultra-thin SiO₂ core-triple shell Au@SiO₂@Ag@SiO₂ for ultra-sensitive trinitrotoluene...

Nanostructured hybrid Au@SiO₂@Ag@SiO₂ was developed, which greatly enhanced the surface plasmon resonance effect due to the interfacial effect of dual ultra-thin SiO₂ in which the double-superimposed long-range plasmon transfer between Au and Ag and determinand molecules. In addition, the interfacial effect between the inner and outermost silica layer can contribute to the presence of an amplified electric field between Au core and Ag shell, which prevents aggregation and oxidation of nanoparticles. At the same time, the influence of the amount of silica in SiO₂ shells on the Surface Enhanced Raman Scattering (SERS) was explored by controlling the experimental conditions. In our experiments, the ultrathin silica coating Au@SiO₂@Ag@SiO₂ showed the best SERS performance, generating an analytical enhancement factor (AEF) of 5 × 10⁶. At the same time, nanoparticles modified by 4-aminothiophenol (4-ATP) can detect 2,4,6-TNT as low as 2.27 × 10^-6 ppb (10^-14 M) and exhibit excellent versatility in the detection of nitroaromatics. The results demonstrated that the interfacial effect of double-layer dielectric silica achieved the localized surface plasmon resonance enhancement effect in Au@SiO₂@Ag@SiO₂.