Fabrication of Au_nanoparticle@mSiO₂@Y₂O₃:Eu nanocomposites with enhanced fluorescence

Herein, Au_nanoparticle@mSiO₂@Y₂O₃:Eu nanocomposites are synthesized through layer-by-layer assembly technology. Au_nanoparticle@mSiO₂ core-shell nanospheres were prepared at first in the presence of CTAB in aqueous solution system by the modified one-pot method. A chemical precipitation method and a succeeding calcination process were adopted to the growth of Y₂O₃:Eu shells on the surfaces of Au_nanoparticle@mSiO₂ core-shell nanospheres. The structure, morphology and composition of the nanocomposites were confirmed by XRD, TEM and UV-vis absorption spectrum. The prepared Au_nanoparticle@mSiO₂@Y₂O₃:Eu nanocomposites have showed the emission intensity enhances to 6.23 times at 30 nm thickness of the silica spacer between the core of Au nanoparticle and the shell of Y₂O₃:Eu. According to the observations of fluorescent lifetime and the modeling of local electric field, the metal-enhanced and quenched fluorescence is closely related with the enhancement of excitation and radiative decay rate and the quenching by NRET comes as a result of competition between the distance-dependent mechanisms. This kind of multifunctional inorganic material will be widely used in electronics, biology and medical drug loading, etc.