One-Step Preparation and Fluorescence Enhancement Effect in SiO₂/Eu²⁺ Doped with Ag Nanowires

Eu²⁺ single-doped SiO₂ (SiO₂/Eu²⁺) and Eu²⁺, Ag nanowires co-doped SiO₂ (SiO₂/Eu²⁺-Ag) luminescent nanomaterials were prepared by an efficient one-step sol-gel method. Their microstructure and optical properties were characterized, and the fluorescence enhancement of Eu²⁺ by Ag nanowires was investigated. The experimental results indicate that the average diameter of Ag nanowires doped is 12.5 nm, and the length-diameter ratio is 30. The Ag nanowires cannot only enhance the light absorption of SiO₂/Eu²⁺ in the range of 230-350 nm, but also reduce the fluorescence lifetime of Eu²⁺. More importantly, the emission intensity is enhanced after doping Ag nanowires, and the red shift phenomenon of the emission spectrum is observed, red shift occurs between 10 and 56 nm. The highest fluorescence intensity is accessed under the Ag doping concentration of 0.10 %. Additionally, the emission of SiO₂/Eu²⁺ with 0.10 % of Ag doping at 456 nm is 16 times stronger than that of pure SiO₂/Eu²⁺. The present results indicate that the fluorescence enhancement is attributed to the local field enhancement and the increased radiative decay rates induced by Ag nanowires.