TY  - JOUR
AU  - Meierhofer, Florian
AU  - Weigert, Florian
AU  - Dissinger, Frank
AU  - Jungclaus, Jörgen
AU  - Müller-Caspary, Knut
AU  - Waldvogel, Siegfried R.
AU  - Resch-Genger, Ute
AU  - Voss, Tobias
TI  - Citric Acid Based Carbon Dots with Amine Type Stabilizers: pH-Specific Luminescence and Quantum Yield Characteristics
JO  - The journal of physical chemistry  / C
VL  - 124
IS  - 16
SN  - 1932-7455
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2021-02908
SP  - 8894 - 8904
PY  - 2020
AB  - We report the synthesis and spectroscopic characteristics of two different sets of carbon dots (CDs) formed by hydrothermal reaction between citric acid and polyethylenimine (PEI) or 2,3-diaminopyridine (DAP). Although the formation of amide-based species and the presence of citrazinic acid type derivates assumed to be responsible for a blue emission is confirmed for both CDs by elemental analysis, infrared spectroscopy, and mass spectrometry, a higher abundance of sp2-hybridized nitrogen is observed for DAP-based CDs, which causes a red-shift of the n-π* absorption band relative to the one of PEI-based CDs. These CD systems possess high photoluminescence quantum yields (QY) of ∼40% and ∼48% at neutral pH, demonstrating a possible tuning of the optical properties by the amine precursor. pH-Dependent spectroscopic studies revealed a drop in QY to < 9% (pH ∼ 1) and < 21% (pH ∼ 12) for both types of CDs under acidic and basic conditions. In contrast, significant differences in the pH-dependency of the n-π* transitions are found for both CD types which are ascribed to different (de)protonation sequences of the CD-specific fluorophores and functional groups using zeta potential analysis.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000529225800047
DO  - DOI:10.1021/acs.jpcc.9b11732
UR  - https://juser.fz-juelich.de/record/893896
ER  -