TY  - JOUR
A1  - Heyne, Benjamin
A1  - Arlt, Kristin
A1  - Geßner, André
A1  - Richter, Alexander F.
A1  - Döblinger, Markus
A1  - Feldmann, Jochen
A1  - Taubert, Andreas
A1  - Wedel, Armin
T1  - Mixed Mercaptocarboxylic Acid Shells Provide Stable Dispersions of InPZnS/ZnSe/ZnS Multishell Quantum Dots in Aqueous Media
JF  - Nanomaterials
N2  - Highly luminescent indium phosphide zinc sulfide (InPZnS) quantum dots (QDs), with zinc selenide/zinc sulfide (ZnSe/ZnS) shells, were synthesized. The QDs were modified via a post-synthetic ligand exchange reaction with 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) in different MPA:MUA ratios, making this study the first investigation into the effects of mixed ligand shells on InPZnS QDs. Moreover, this article also describes an optimized method for the correlation of the QD size vs. optical absorption of the QDs. Upon ligand exchange, the QDs can be dispersed in water. Longer ligands (MUA) provide more stable dispersions than short-chain ligands. Thicker ZnSe/ZnS shells provide a better photoluminescence quantum yield (PLQY) and higher emission stability upon ligand exchange. Both the ligand exchange and the optical properties are highly reproducible between different QD batches. Before dialysis, QDs with a ZnS shell thickness of ~4.9 monolayers (ML), stabilized with a mixed MPA:MUA (mixing ratio of 1:10), showed the highest PLQY, at ~45%. After dialysis, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with a mixed MPA:MUA and a ratio of 1:10 and 1:100, showed the highest PLQYs, of ~41%. The dispersions were stable up to 44 days at ambient conditions and in the dark. After 44 days, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with only MUA, showed the highest PLQY, of ~34%.
KW  - quantum dots
KW  - cadmium-free
KW  - Cd-free
KW  - InP
KW  - InPZnS
KW  - multishell
KW  - mercaptocarboxylic acids
KW  - 3-mercaptopropionic acid
KW  - 11-mercaptoundecanoic acid
KW  - phase transfer
KW  - ligand exchange
KW  - aqueous dispersion
KW  - QDs
Y1  - 2020
U6  - https://doi.org/10.3390/nano10091858
SN  - 2079-4991
VL  - 10
IS  - 9
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Wolff, Christian Michael
A1  - Frischmann, Peter D.
A1  - Schulze, Marcus
A1  - Bohn, Bernhard J.
A1  - Wein, Robin
A1  - Livadas, Panajotis
A1  - Carlson, Michael T.
A1  - Jäckel, Frank
A1  - Feldmann, Jochen
A1  - Würthner, Frank
A1  - Stolarczyk, Jacek K.
T1  - All-in-one visible-light-driven water splitting by combining nanoparticulate and molecular co-catalysts on CdS nanorods
JF  - Nature Energy
N2  - Full water splitting into hydrogen and oxygen on semiconductor nanocrystals is a challenging task; overpotentials must be overcome for both half-reactions and different catalytic sites are needed to facilitate them. Additionally, efficient charge separation and prevention of back reactions are necessary. Here, we report simultaneous H-2 and O-2 evolution by CdS nanorods decorated with nanoparticulate reduction and molecular oxidation co-catalysts. The process proceeds entirely without sacrificial agents and relies on the nanorod morphology of CdS to spatially separate the reduction and oxidation sites. Hydrogen is generated on Pt nanoparticles grown at the nanorod tips, while Ru(tpy)(bpy)Cl-2-based oxidation catalysts are anchored through dithiocarbamate bonds onto the sides of the nanorod. O-2 generation from water was verified by O-18 isotope labelling experiments, and time-resolved spectroscopic results confirmed efficient charge separation and ultrafast electron and hole transfer to the reaction sites. The system demonstrates that combining nanoparticulate and molecular catalysts on anisotropic nanocrystals provides an effective pathway for visible-light-driven photocatalytic water splitting.
Y1  - 2018
U6  - https://doi.org/10.1038/s41560-018-0229-6
SN  - 2058-7546
VL  - 3
IS  - 10
SP  - 862
EP  - 869
PB  - Nature Publ. Group
CY  - London
ER  -