Preparation and Upconversion Luminescence of <I>β</I>-NaYF<SUB>4</SUB>:Yb<SUP>3+</SUP>, Tm<SUP>3+</SUP>/ZnO Nanoparticles

Abstract

Beta-NaYF4:Yb3+, Tm3+/ZnO core/shell nanoparticles (NPs) were synthesized via a high temperature thermal decomposition method. The as-synthesized core/shell NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and upconversion luminescence spectra (UCL). Under 980 nm laser excitation, the measured intensity of upconversion luminescence (1I6 --> 3H6, 1I6 --> 3F4, and 1D2 --> 3H6) was different with and without ZnO. During the sample preparations, changing the ratio of the solvent affected the ZnO UV absorption efficiency. The results show that the NIR light can be used as the driving source to excite ZnO, thus extending utility rate to the NIR spectral region and enhancing the light harvest rate.

Synthesis of Reduced Grapheme Oxide as A Platform for loading β-NaYF4:Ho3+@TiO2Based on An Advanced Visible Light-Driven Photocatalyst

“…In order to efficiently utilize the valuable UC energy transferred from the excited UC core, a coupling model was proposed to increase the luminous efficiency, of which the core-shell structure has potential in protecting the UC core from surface quenching and in increasing the efficiency of transferring energy to the photocatalyst shell 25–28 . For examples, the preparation of (α, β)-NaYF 4 :Yb 3+ ,Tm 3+ @TiO 2 , YF 3 :Yb 3+ ,Tm 3+ @TiO 2 , and Y 2 O 3 :Yb 3+ has been reported, wherein the core-shell composite of UC@TiO 2 can emit UV and Vis and show an effective photocatalysis under NIR light 29–33 .…”

Effect of Reduced Grapheme Oxide in Enhancing the Photocatalytic Activity of β-NaYF&lt;sub&gt;4&lt;/sub&gt;:Ho&lt;sup&gt;3+&lt;/sup&gt;@TiO&lt;sub&gt;2&lt;/sub&gt;

“…Recently, there have been reports of the combination of upconversion luminescence (UC) agents with the semiconductors, which allowed the use of a visible or NIR light source for catalysis [8][9][10]. In order to efficiently utilize the valuable upconversion energy transferred from the excited upconversion core [11]. The core-shell structure has potential, which can protect the upconversion core from surface quenching and increase the energy transfer efficiency to the photocatalyst shell.…”

Synthesis and photocatalytic activity of hexagonal phase NaYF4:Ho3+@TiO2core–shell microcrystals

“…Compared with YF 3 and LiYF 4 , rareearth-doped NaYF 4 is a more effective UC material that can emit bright light, such as UV light, under NIR light or visible light excitation. 32,33 Hence, NaYF 4 might serve as an intermediate that, after absorbing NIR light or visible light, emits high-energy UV light that can be absorbed by TiO 2 , resulting in efficient photocatalytic reactions. 34 The absorption of UV light from the UC luminescent material by TiO 2 does not change its properties.…”