Ein Simulationsmodell für den Protonentransfer auf Metalloberflächen
Auch gedruckt in der BibliothekW: W-H 12.852
FakultätFakultät für Naturwissenschaften
Ressourcen- / MedientypDissertation, Text
Datum der Freischaltung2012-04-24
The objective of this thesis was to develop a new model for the electrochemical proton transfer to metal electrodes to be used within the framework of classical molecular dynamics simulations. Employing this model, a detailed analysis of the reaction was to be performed for two metals, platinum and silver, which are characteristic examples of a very good and a rather inferior catalyst for hydrogen evolution, respectively. In particular, reproducing the different behaviour of the two metals as found in experiment and providing deeper insight into the respective causes was aimed at. The empirical valence bond model developed for this thesis is an extension of a model for the description of proton transfer within the aqueous phase featuring two diabatic states, which has been described in literature. The extended model now comprises nine states, thereby the additional states allow for the description of bond breaking and formation at the (111)-surface of the metal. Thus, a quasi quantum-mechanical description of the reaction within classical molecular dynamics simulations becomes feasible. Employing the new model to perform molecular dynamics simulations, the onset of the reaction could be observed within the expected potential range and the differences between both metals could be reproduced in a fairly good manner. Furthermore, more detailed investigations on the reaction kinetics and mechanism were performed. Altogether, the model developed here supplements the theoretical methods traditionally used to investigate electrochemical proton transfer in a sensible way. In particular, the studies performed for this thesis have clearly illustrated the relevancy of describing the dynamics of the surrounding solvent correctly; together with the options for detailed analysis of the reaction mechanism, this constitutes a valuable benefit of the method used herein.
Proton transfer reactions