TY  - JOUR
A1  - Harmanli, İpek
A1  - Tarakina, Nadezda
A1  - Antonietti, Markus
A1  - Oschatz, Martin
T1  - "Giant" nitrogen uptake in ionic liquids confined in carbon pores
JF  - Journal of the American Chemical Society
N2  - Ionic liquids are well known for their high gas absorption capacity. It is shown that this is not a solvent constant, but can be enhanced by another factor of 10 by pore confinement, here of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EmimOAc) in the pores of carbon materials. A matrix of four different carbon compounds with micro- and mesopores as well as with and without nitrogen doping is utilized to investigate the influence of the carbons structure on the nitrogen uptake in the pore-confined EmimOAc. In general, the absorption is most improved for IL in micropores and in nitrogen-doped carbon. This effect is so large that it is already seen in TGA and DSC experiments. Due to the low vapor pressure of the IL, standard volumetric sorption experiments can be used to quantify details of this effect. It is reasoned that it is the change of the molecular arrangement of the ions in the restricted space of the pores that creates additional free volume to host molecular nitrogen.
Y1  - 2021
U6  - https://doi.org/10.1021/jacs.1c00783
SN  - 0002-7863
SN  - 1520-5126
VL  - 143
IS  - 25
SP  - 9377
EP  - 9384
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Hwang, Jongkook
A1  - Walczak, Ralf
A1  - Oschatz, Martin
A1  - Tarakina, Nadezda
A1  - Schmidt, Bernhard V. K. J.
T1  - Micro-Blooming: Hierarchically Porous Nitrogen-Doped Carbon Flowers Derived from Metal-Organic Mesocrystals
JF  - Small
N2  - Synthesis of 3D flower-like zinc-nitrilotriacetic acid (ZnNTA) mesocrystals and their conformal transformation to hierarchically porous N-doped carbon superstructures is reported. During the solvothermal reaction, 2D nanosheet primary building blocks undergo oriented attachment and mesoscale assembly forming stacked layers. The secondary nucleation and growth preferentially occurs at the edges and defects of the layers, leading to formation of 3D flower-like mesocrystals comprised of interconnected 2D micropetals. By simply varying the pyrolysis temperature (550-1000 degrees C) and the removal method of in the situ-generated Zn species, nonporous parent mesocrystals are transformed to hierarchically porous carbon flowers with controllable surface area (970-1605 m(2) g(-1)), nitrogen content (3.4-14.1 at%), pore volume (0.95-2.19 cm(3) g(-1)), as well as pore diameter and structures. The carbon flowers prepared at 550 degrees C show high CO2/N-2 selectivity due to the high nitrogen content and the large fraction of (ultra)micropores, which can greatly increase the CO2 affinity. The results show that the physicochemical properties of carbons are highly dependent on the thermal transformation and associated pore formation process, rather than directly inherited from parent precursors. The present strategy demonstrates metal-organic mesocrystals as a facile and versatile means toward 3D hierarchical carbon superstructures that are attractive for a number of potential applications.
KW  - 3D flower superstructures
KW  - hierarchically porous carbon
KW  - metal-organic mesocrystals
KW  - thermal transformation mechanism
Y1  - 2019
U6  - https://doi.org/10.1002/smll.201901986
SN  - 1613-6810
SN  - 1613-6829
VL  - 15
IS  - 37
PB  - Wiley-VCH
CY  - Weinheim
ER  -