TY  - JOUR
A1  - Hesse, Julia
A1  - Klier, Dennis Tobias
A1  - Sgarzi, Massimo
A1  - Nsubuga, Anne
A1  - Bauer, Christoph
A1  - Grenzer, Joerg
A1  - Hübner, Rene
A1  - Wislicenus, Marcus
A1  - Joshi, Tanmaya
A1  - Kumke, Michael Uwe
A1  - Stephan, Holger
T1  - Rapid Synthesis of Sub-10nm Hexagonal NaYF4-Based Upconverting Nanoparticles using Therminol((R))66
JF  - ChemistryOpen : including thesis treasury
N2  - We report a simple one-pot method for the rapid preparation of sub-10nm pure hexagonal (-phase) NaYF4-based upconverting nanoparticles (UCNPs). Using Therminol((R))66 as a co-solvent, monodisperse UCNPs could be obtained in unusually short reaction times. By varying the reaction time and reaction temperature, it was possible to control precisely the particle size and crystalline phase of the UCNPs. The upconversion (UC) luminescence properties of the nanocrystals were tuned by varying the concentrations of the dopants (Nd3+ and Yb3+ sensitizer ions and Er3+ activator ions). The size and phase-purity of the as-synthesized core and core-shell nanocrystals were assessed by using complementary transmission electron microscopy, dynamic light scattering, X-ray diffraction, and small-angle X-ray scattering studies. In-depth photophysical evaluation of the UCNPs was pursued by using steady-state and time-resolved luminescence spectroscopy. An enhancement in the UC intensity was observed if the nanocrystals, doped with optimized concentrations of lanthanide sensitizer/activator ions, were further coated with an inert/active shell. This was attributed to the suppression of surface-related luminescence quenching effects.
KW  - core-shell materials
KW  - lanthanides
KW  - nanostructures
KW  - photoluminescence
KW  - upconversion
Y1  - 2018
U6  - https://doi.org/10.1002/open.201700186
SN  - 2191-1363
VL  - 7
IS  - 2
SP  - 159
EP  - 168
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Xu, Jingsan
A1  - Brenner, Thomas J. K.
A1  - Chen, Zupeng
A1  - Neher, Dieter
A1  - Antonietti, Markus
A1  - Shalom, Menny
T1  - Upconversion-agent induced improvement of g-C3N4 photocatalyst under visible light
JF  - ACS applied materials & interfaces
N2  - Herein, we report the use of upconversion agents to modify graphite carbon nitride (g-C3N4) by direct thermal condensation of a mixture of ErCl3 center dot 6H(2)O and the supramolecular precursor cyanuric acid-melamine. We show the enhancement of g-C3N4 photoactivity after Er3+ doping by monitoring the photodegradation of Rhodamine B dye under visible light. The contribution of the upconversion agent is demonstrated by measurements using only a red laser. The Er3+ doping alters both the electronic and the chemical properties of g-C3N4. The Er3+ doping reduces emission intensity and lifetime, indicating the formation of new, nonradiative deactivation pathways, probably involving charge-transfer processes.
KW  - metal-free photocatalysis
KW  - upconversion
KW  - carbon nitride
KW  - RhB photodegradation
Y1  - 2014
U6  - https://doi.org/10.1021/am5051263
SN  - 1944-8244
VL  - 6
IS  - 19
SP  - 16481
EP  - 16486
PB  - American Chemical Society
CY  - Washington
ER  -