TY  - GEN
A1  - Ehlert, Christopher
A1  - Holzweber, Markus
A1  - Lippitz, Andreas
A1  - Unger, Wolfgang E. S.
A1  - Saalfrank, Peter
T1  - A detailed assignment of NEXAFS resonances of imidazolium based ionic liquids
N2  - In Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy X-Ray photons are used to excite tightly bound core electrons to low-lying unoccupied orbitals of the system. This technique offers insight into the electronic structure of the system as well as useful structural information. In this work, we apply NEXAFS to two kinds of imidazolium based ionic liquids ([CnC1im]+[NTf2]- and [C4C1im]+[I]-). A combination of measurements and quantum chemical calculations of C K and N K NEXAFS resonances is presented. The simulations, based on the transition potential density functional theory method (TP-DFT), reproduce all characteristic features observed by the experiment. Furthermore, a detailed assignment of resonance features to excitation centers (carbon or nitrogen atoms) leads to a consistent interpretation of the spectra.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 315 
KW  - ray absorption-spectroscopy
KW  - fine-structure
KW  - spectra
KW  - simulations
KW  - molecules
KW  - dynamics
KW  - graphene
KW  - surface
KW  - salts
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-394417
SP  - 8654
EP  - 8661
ER  - 
TY  - GEN
A1  - Wirth, Jonas
A1  - Neumann, Rainer
A1  - Antonietti, Markus
A1  - Saalfrank, Peter
T1  - Adsorption and photocatalytic splitting of water on graphitic carbon nitride
BT  - a combined first principles and semiempirical study
N2  - Graphitic carbon nitride, g-C₃N₄, is a promising organic photo-catalyst for a variety of redox reactions. In order to improve its efficiency in a systematic manner, however, a fundamental understanding of the microscopic interaction between catalyst, reactants and products is crucial. Here we present a systematic study of water adsorption on g-C₃N₄ by means of density functional theory and the density functional based tight-binding method as a prerequisite for understanding photocatalytic water splitting. We then analyze this prototypical redox reaction on the basis of a thermodynamic model providing an estimate of the overpotential for both water oxidation and H⁺ reduction. While the latter is found to occur readily upon irradiation with visible light, we derive a prohibitive overpotential of 1.56 eV for the water oxidation half reaction, comparing well with the experimental finding that in contrast to H₂ production O₂ evolution is only possible in the presence of oxidation cocatalysts.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 172 
KW  - augmented-wave method
KW  - hydrogen
KW  - initio molecular-dynamics
KW  - oxidation
KW  - photooxidation
KW  - reduction
KW  - simulations
KW  - tight-binding
KW  - transition
KW  - visible-light
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-74391
SP  - 15917
EP  - 15926
ER  - 
TY  - JOUR
A1  - Wirth, Jonas
A1  - Neumann, Rainer
A1  - Antonietti, Markus
A1  - Saalfrank, Peter
T1  - Adsorption and photocatalytic splitting of water on graphitic carbon nitride
BT  - a combined first principles and semiempirical study
JF  - physical chemistry, chemical physics : PCCP
N2  - Graphitic carbon nitride, g-C₃N₄, is a promising organic photo-catalyst for a variety of redox reactions. In order to improve its efficiency in a systematic manner, however, a fundamental understanding of the microscopic interaction between catalyst, reactants and products is crucial. Here we present a systematic study of water adsorption on g-C₃N₄ by means of density functional theory and the density functional based tight-binding method as a prerequisite for understanding photocatalytic water splitting. We then analyze this prototypical redox reaction on the basis of a thermodynamic model providing an estimate of the overpotential for both water oxidation and H⁺ reduction. While the latter is found to occur readily upon irradiation with visible light, we derive a prohibitive overpotential of 1.56 eV for the water oxidation half reaction, comparing well with the experimental finding that in contrast to H₂ production O₂ evolution is only possible in the presence of oxidation cocatalysts.
KW  - initio molecular-dynamics
KW  - augmented-wave method
KW  - visible-light
KW  - tight-binding
KW  - transition
KW  - oxidation
KW  - photooxidation
KW  - simulations
KW  - reduction
KW  - hydrogen
Y1  - 2014
U6  - https://doi.org/10.1039/c4cp02021a
SN  - 1463-9076
SN  - 1463-9084
VL  - 2014
IS  - 16
SP  - 15917
EP  - 15926
ER  -