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  - GEN
A1  - Banerjee, Shiladitya
A1  - Saalfrank, Peter
T1  - Vibrationally resolved absorption, emission and resonance Raman spectra of diamondoids
BT  - a study based on time-dependent correlation functions
N2  - The time-dependent approach to electronic spectroscopy, as popularized by Heller and coworkers in the 1980's, is applied here in conjunction with linear-response, time-dependent density functional theory to study vibronic absorption, emission and resonance Raman spectra of several diamondoids. Two-state models, the harmonic and the Condon approximations, are used for the calculations, making them easily applicable to larger molecules. The method is applied to nine pristine lower and higher diamondoids: adamantane, diamantane, triamantane, and three isomers each of tetramantane and pentamantane. We also consider a hybrid species “Dia = Dia” – a shorthand notation for a recently synthesized molecule comprising two diamantane units connected by a C[double bond, length as m-dash]C double bond. We resolve and interpret trends in optical and vibrational properties of these molecules as a function of their size, shape, and symmetry, as well as effects of “blending” with sp2-hybridized C-atoms. Time-dependent correlation functions facilitate the computations and shed light on the vibrational dynamics following electronic transitions.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 238 
KW  - adamantane
KW  - models
KW  - molecules
KW  - states
KW  - thermochemistry
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-94542
SP  - 144
EP  - 158
ER  -