Quantitative evaluation for the contribution of each component in NaYF4: Yb, Tm@NaYF4: Yb, Ho@NaYF4 upconversion nanoparticle: Active shell, inert shell, size, and their cooperation

Development of the upconversion nanoparticles/metal organic frameworks (UCNPs/MOFs) covering the full solar light spectrum, especially for the near infrared (NIR) light, is an robust strategy to improve the photocatalytic activity. However, the low upconversion efficiency is still an obstacle in the photocatalytic process. Introduction of shell to construct the core-shell or core-shell-shell upconversion nanoparticles is a feasible and popular pathway to refine the upconversion efficiency. However, the contribution of each component and their synergistic cooperation is still obscure, especially for the quantitative evaluation. A series of upconversion nanoparticles, NaYF4: Yb, Tm (TM), NaYF4: Yb, Tm@NaYF4: Yb, Ho (TM@HO), and NaYF4: Yb, Tm@NaYF4: Yb, Ho@NaYF4 (TM@HO@Y), are fabricated to account the contribution of active shell, inert shell, and their cooperation. Furthermore, the NaYF4: Yb, Tm (NYT, the size is different with that of TM) and NaYF4: Yb, Tm@NaYF4 (TM@Y) are also developed by the controlled synthesis with the same size as TM@HO@Y to avoid the size influence. According to the luminescent spectrum feature, the contribution of each part is fitted into a linear equation. By combination of NH2-UiO-66 (Zr) (NU), the hybrid photocatalysts are developed and their photocatalytic performance is measured by degradation of antibiotics and organic pollutant. This work sheds light on the quantitatively elucidating the contribution of each component, which is helpful to design the robust upconversion nanoparticles with the desired upconversion efficiency by tuning the component.