TY  - JOUR
A1  - Chen, Zupeng
A1  - Savateev, Aleksandr
A1  - Pronkin, Sergey
A1  - Papaefthimiou, Vasiliki
A1  - Wolff, Christian Michael
A1  - Willinger, Marc Georg
A1  - Willinger, Elena
A1  - Neher, Dieter
A1  - Antonietti, Markus
A1  - Dontsova, Dariya
T1  - "The Easier the Better" Preparation of Efficient Photocatalysts-Metastable Poly(heptazine imide) Salts
JF  - Advanced materials
N2  - Cost-efficient, visible-light-driven hydrogen production from water is an attractive potential source of clean, sustainable fuel. Here, it is shown that thermal solid state reactions of traditional carbon nitride precursors (cyanamide, melamine) with NaCl, KCl, or CsCl are a cheap and straightforward way to prepare poly(heptazine imide) alkali metal salts, whose thermodynamic stability decreases upon the increase of the metal atom size. The chemical structure of the prepared salts is confirmed by the results of X-ray photoelectron and infrared spectroscopies, powder X-ray diffraction and electron microscopy studies, and, in the case of sodium poly(heptazine imide), additionally by atomic pair distribution function analysis and 2D powder X-ray diffraction pattern simulations. In contrast, reactions with LiCl yield thermodynamically stable poly(triazine imides). Owing to the metastability and high structural order, the obtained heptazine imide salts are found to be highly active photo-catalysts in Rhodamine B and 4-chlorophenol degradation, and Pt-assisted sacrificial water reduction reactions under visible light irradiation. The measured hydrogen evolution rates are up to four times higher than those provided by a benchmark photocatalyst, mesoporous graphitic carbon nitride. Moreover, the products are able to photocatalytically reduce water with considerable reaction rates, even when glycerol is used as a sacrificial hole scavenger.
KW  - carbon nitride
KW  - glycerol oxidation
KW  - mesocrystals
KW  - poly(heptazine imide)
KW  - water reduction reactions
Y1  - 2017
U6  - https://doi.org/10.1002/adma.201700555
SN  - 0935-9648
SN  - 1521-4095
VL  - 29
SP  - 21800
EP  - 21806
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Walczak, Ralf
A1  - Savateev, Aleksandr
A1  - Heske, Julian
A1  - Tarakina, Nadezda V.
A1  - Sahoo, Sudhir
A1  - Epping, Jan D.
A1  - Kuehne, Thomas D.
A1  - Kurpil, Bogdan
A1  - Antonietti, Markus
A1  - Oschatz, Martin
T1  - Controlling the strength of interaction between carbon dioxide and nitrogen-rich carbon materials by molecular design
JF  - Sustainable energy & fuels
N2  - Thermal treatment of hexaazatriphenylene-hexacarbonitrile (HAT-CN) in the temperature range from 500 degrees C to 700 degrees C leads to precise control over the degree of condensation, and thus atomic construction and porosity of the resulting C2N-type materials. Depending on the condensation temperature of HAT-CN, nitrogen contents of more than 30 at% can be reached. In general, these carbons show adsorption properties which are comparable to those known for zeolites but their pore size can be adjusted over a wider range. At condensation temperatures of 525 degrees C and below, the uptake of nitrogen gas remains negligible due to size exclusion, but the internal pores are large and polarizing enough that CO2 can still adsorb on part of the internal surface. This leads to surprisingly high CO2 adsorption capacities and isosteric heat of adsorption of up to 52 kJ mol(-1). Theoretical calculations show that this high binding enthalpy arises from collective stabilization effects from the nitrogen atoms in the C2N layers surrounding the carbon atom in the CO2 molecule and from the electron acceptor properties of the carbon atoms from C2N which are in close proximity to the oxygen atoms in CO2. A true CO2 molecular sieving effect is achieved for the first time in such a metal-free organic material with zeolite-like properties, showing an IAST CO2/N-2 selectivity of up to 121 at 298 K and a N-2/CO2 ratio of 90/10 without notable changes in the CO2 adsorption properities over 80 cycles.
Y1  - 2019
U6  - https://doi.org/10.1039/c9se00486f
SN  - 2398-4902
VL  - 3
IS  - 10
SP  - 2819
EP  - 2827
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -