Improving photocatalytic activity by combining upconversion nanocrystals and Mo-doping: a case study on β-NaLuF₄:Gd,Yb,Tm@SiO₂@TiO₂:Mo

Abstract

A novel double-shell-structured β-NaLuF 4 : Gd,Yb,Tm@SiO 2 @TiO 2 :Mo nanocomposite photocatalyst has been developed for the first time. The nanocomposite consists of uniform β-NaLuF 4 : Gd, Yb, Tm upconversion nanocrystals as core, a media shell of SiO 2 , and a lot of small sized anatase TiO 2 nanoparticles as the outer shell. The TiO 2 shell is modified by Mo-doping, which can narrow the band-gap of TiO 2 and act as electron traps resulting in enhancement of light absorption and reduction of recombination rate of the photogenerated carriers. The upconversion nanocrystals can convert NIR into UV and visible lights which are overall absorbed by the modified TiO 2 shell. Photocatalytic activities of the prepared products are evaluated through photocatalytic degradation of RhB under the irradiations of simulated solar and NIR lights. The results show that the as-prepared nanocomposite displays a high photocatalytic activity which is significant higher than that of commercial P25 and pure TiO 2 . This work provides new insights into the fabrication of TiO 2 -based composites as high performance photocatalysts and facilitate their application in environmental protection issues using solar light.

Nanocarriers Based on NaTmF4:0.5%Er3+@NaLuF4 Upconversion Nanoparticles with Enhanced Near-Infrared Luminescence for Combination Tumor Treatment

“…27-0726). 25 Highresolution transmission electron microscopy (HRTEM) images revealed the single crystalline attribute, as corroborated by the observed clear lattice fringes with the measured d spacing (0.528 nm), consistent with the lattice spacing of the (100) plane of NaLuF 4 (JCPDS no. 27-0726).…”

“…The powder X-ray diffraction (XRD) pattern showed that as-synthesized U was of a hexagonal phase (Figure S1a), which matched with β-NaLuF 4 (JCPDS no. 27-0726) . High-resolution transmission electron microscopy (HRTEM) images revealed the single crystalline attribute, as corroborated by the observed clear lattice fringes with the measured d spacing (0.528 nm), consistent with the lattice spacing of the (100) plane of NaLuF 4 (JCPDS no.…”

Multicolor Solar Absorption as a Synergetic UV Upconversion Enhancement Mechanism in LiYF4:Yb3+,Tm3+ Nanocrystals

“…Considering the non-linearity of this effect, up-conversion enhanced photocatalysis has only been demonstrated with a relatively high excitation provided by an infrared laser. [9][10][11][12][13][14][15] Nevertheless, we demonstrated previously that up-converting NaGdF 4 :Yb 3+ ,Tm 3+ nanocrystals can also enhance photocatalysis under solar irradiation. 16 This last result was counter-intuitive if one considers that the addition of the energy of at least 3 photons in the IR are required to obtain one excitation in the UV.…”

“…Using upconversion materials to convert many more solar spectrum photons into useful ones could greatly enhance the production rate, provided that they demonstrate the ability to produce UV photons. Considering the nonlinearity of this effect, upconversion-enhanced photocatalysis has only been demonstrated with a relatively high excitation provided by an infrared laser. − Nevertheless, we demonstrated previously that upconverting NaGdF 4 :Yb 3+ ,Tm 3+ nanocrystals can also enhance photocatalysis under solar irradiation . This last result was counterintuitive if one considers that the addition of the energy of at least 3 photons in the IR is required to obtain one excitation in the UV.…”

Improved Self-Cleaning and Spectral Features of Erbium Doped Tellurite Glass with Titania Nanoparticles Sensitization

“…Super hydrophilic surface acts as selfcleaning with water contact angle less than 50 o , which is necessary for a droplet to roll off the surface [3]. Meanwhile, photocatalysis refers a chemical reaction between organic species and free radicals upon irradiation with UV-visible or near-infrared (NIR) light that degrades the harmful pollutant on the glass surface [4]. Among various photocatalysts, titania nanoparticles (TiNPs) are frequently used for self-cleaning purpose due to its strong photocatalytic properties which able to decompose common dye pollutants such as Methylene Blue (MB) [2].…”