Plasmonic properties of Au/SiO2 nanoparticles: effect of gold size and silica dielectric layer thickness

Metallic nanoparticles with plasmonic properties have extensive potential applications in biodiagnostics and sensing, bioimaging and solar cells, but a comprehensive theoretical and experimental investigation of the phenomenon is far from being complete. In this manuscript, about 30, 40 and 50 nm Au nanoparticles were synthesised by Frens method, and Au/SiO2 nanoparticles were obtained by a modified Stober method; the thickness of SiO2 layer were adjusted from 15 to 45 nm. The effect of Au size and SiO2 dielectric layer thickness on the plasmonic properties of Au/SiO2 nanoparticles were numerically simulated by 3D comsol and were experimentally studied by UV-vis absorption spectra. UV-vis absorption spectra showed that the increase in Au particle size or SiO2 thickness resulted in a red shift of the surface plasmon resonance absorption peak of Au/SiO2 nanoparticles, which is consistent with the simulation results by 3D comsol. Thicker SiO2 layer and smaller Au nanoparticles led to the decrease of electric field.