Heidelberg 2015 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 12: Photochemistry and Catalysis
MO 12.4: Vortrag
Mittwoch, 25. März 2015, 12:00–12:15, PH/HS1
Light-Driven Electron and Energy Transfer in a Photocatalytic Model System — •Aleksej Friedrich1, Esteban Mejía2, Shu-Ping Luo2, Henrik Junge2, Matthias Beller2, and Stefan Lochbrunner1 — 1Institute of Physics, University of Rostock, 18051 Rostock, Germany — 2Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein-Str. 29a, 18059 Rostock, Germany
A promising route to provide environmentally friendly energy is the generation of solar fuels by photocatalysis. We investigate a hydrogen evolving homogeneous photocatalytic model system consisting of a non-noble metal-photosensitizer (PS), an iron-catalyst, and triethylamine (TEA) as a sacrificial reductant.[1,2] So far little is known, about the fundamental reaction steps and possible loss channels. Here we study the intermolecular electron and energy transfer by time resolved luminescence and transient absorption spectroscopy on the nanosecond timescale. It is found that 20 vol% of the sacrificial reductant reduces the luminescence lifetime of the copper-PS in acetonitrile moderately from 280 ns to 210 ns. Contrary, the iron-catalyst quenches the lifetime more efficiently to 110 ns. Long living products of the quenching events are observed by the transient absorption measurements. To identify the products and to determine the transfer yield control experiments with the strong electron acceptor methyl viologen are performed. By comparison the electron transfer efficiency from the PS to the catalyst is determined to 4%.
Literature: [1] S. Luo et al., Angew. Chem. 125, 437-441 (2012). [2] E. Mejía et al., Chem. Eur. J. 19, 15972-15978 (2013).