Ultrafast two-colour X-ray emission spectroscopy reveals excited state landscape in a base metal dyad

Effective photoinduced charge transfer makes molecular bimetallic assemblies attractive for applications as active light induced proton reduction systems. For a more sustainable future, development of competitive base metal dyads is mandatory. However, the electron transfer mechanisms from the photo...

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Published in:arXiv.org 2023-01
Main Authors: Nowakowski, Michal, Huber-Gedert, Marina, Elgabarty, Hossam, Kubicki, Jacek, Kertem, Ahmet, Lindner, Natalia, Khakhulin, Dmitry, Frederico Alves Lima, Choi, Tae-Kyu, Biednov, Mykola, Piergies, Natalia, Zalden, Peter, Kubicek, Katerina, Rodriguez-Fernandez, Angel, Salem, Mohammad Alaraby, Kühne, Thomas, Gawelda, Wojciech, Bauer, Matthias
Format: Article
Language:English
Subjects:
Base metal
Bimetals
Catalysts
Charge transfer
Cobalt
Color
Electron transfer
Emission spectroscopy
Excitation
Excitation spectra
Hydrogen production
Iron
Photoexcitation
Protons
Reduction (metal working)
Spectrum analysis
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Summary:Effective photoinduced charge transfer makes molecular bimetallic assemblies attractive for applications as active light induced proton reduction systems. For a more sustainable future, development of competitive base metal dyads is mandatory. However, the electron transfer mechanisms from the photosensitizer to the proton reduction catalyst in base metal dyads remain so far unexplored. We study a Fe-Co dyad that exhibits photocatalytic H2 production activity using femtosecond X-ray emission spectroscopy, complemented by ultrafast optical spectroscopy and theoretical time-dependent DFT calculations, to understand the electronic and structural dynamics after photoexcitation and during the subsequent charge transfer process from the FeII photosensitizer to the cobaloxime catalyst. Using this novel approach, the simultaneous measurement of the transient Kalpha X-ray emission at the iron and cobalt K-edges in a two-colour experiment is enabled making it possible to correlate the excited state dynamics to the electron transfer processes. The methodology, therefore, provides a clear and direct spectroscopic evidence of the Fe->Co electron transfer responsible for the proton reduction activity.
ISSN:2331-8422