Silver/graphene-coated silicon dioxide composite upconversion nanocrystal and preparation method thereof

Abstract

The invention relates to a silver/graphene-coated silicon dioxide composite upconversion nanocrystal and a preparation method thereof. The nanocrystal structure of the obtained silver/graphene@SiO2-NaLuF4:Yb,Gd,Er composite fluorescent nanoparticles is as follows: silver-on-graphene is used as an inner core and coated with silicon dioxide, and the upconversion nanocrystal is grafted onto the silicon dioxide surface. The metal reinforced fluorescence effect of the noble metal silver is utilized to enhance the luminescent intensity of the upconversion nanocrystal. The silver is supported on the graphene to well prevent the silver particles from aggregation, and the silver nanoparticles, which are dispersed and fixed to the graphene, generate field effect superposition due to short distance, so that the mutual polarity and surface plasma resonance are mutually reinforced. Since the graphene is an excellent electron acceptor and conductor, after the charges of the silver nanoparticles transfer to the graphene, the electron density becomes lower, the effective dielectric constant increases, and thus, the surface plasma resonance of the nano silver is enhanced, so that the metal reinforced fluorescence effect of the nano silver becomes higher. The method enhances the upconversion luminescent intensity of the rare-earth upconversion nanocrystal by about 50 times.

Description

technical field [0001] The invention relates to a silver graphene-coated silicon dioxide composite up-conversion nanocrystal and a preparation method thereof. Background technique [0002] The ordered π-bond electronic structure on graphene endows it with unique thermal, mechanical, electrical, and mechanical properties. The theoretical thermal conductivity of graphene can reach 5000 W / (m·K), the strength can reach 130 GPa, and its carrier mobility can reach 15000 cm2 / (V·S). The exotic physical and chemical properties such as magnetism make it have potential applications in the fields of physics, chemistry and biology. Due to its special electronic structure and huge specific surface area, Ag nanoparticles have important applications in the catalysis of chemical reactions, surface-enhanced Raman scattering, sensing, biomarkers, and antibacterial. Current research reports that combining Ag nanoparticles and graphene can obviously achieve the purpose of enhancing the propert...

AI Technical Summary

Problems solved by technology

However, the low luminous efficiency of rare earth upconversion nanocrystals limits its biological application. How to improve the luminescence intensity of upconversion nanocrystals is currently a hot and difficult issue in this field.

[0005] In summary, about silver / graphene SiO 2 -NaLuF 4 : The study of Yb, Gd, Er composite fluorescent nanoparticles has not been reported. In addition, silver / graphene SiO with good upconversion fluorescence properties can be prepared 2 -NaLuF 4 : The scheme or route of Yb, Gd, Er composite fluorescent nanoparticles has not been reported yet

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