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Effective Quenching and Excited-State Relaxation of a Cu(I) Photosensitizer Addressed by Time-Resolved Spectroscopy and TDDFT Calculations

preprint
revised on 14.07.2018 and posted on 16.07.2018 by Aleksej Friedrich, Olga S. Bokareva, Shu-Ping Luo, Henrik Junge, Matthias Beller, Oliver Kühn, Stefan Lochbrunner

Homogenous photocatalytic systems based on copper photosensitizers are promising candidates for noble metal free approaches in solar hydrogen generation. To improve their performance a detailed understanding of the individual steps is needed. Here, we study the interaction of a heteroleptic copper (I) photosensitizer with an iron catalyst by time-resolved spectroscopy and ab-initio calculations. The catalyst leads to rather efficient quenching of the 3MLCT state of the copper complex, with a bimolecular rate being about three times smaller than the collision rate. Using control experiments with methyl viologen an appearing absorption band is assigned to the oxidized copper complex demonstrating that electron transfer from the sensitizer to the iron catalyst occurs and the system reacts along an oxidative pathway. However, only about 30% of the quenching events result in an electron transfer while the other 70% experience deactivation indicating that the photocatalytic performance could be improved by optimizing the intermolecular interaction.


Funding

European Union (European Social Funds, ESF) via the project "PS4H", by the Federal Ministry of Education and Research of Germany via the project "Light to hydrogen" (L2H), German Research Foundation via the collaborative research center SFB 652

History

Email Address of Submitting Author

oliver.kuehn@uni-rostock.de

Institution

University of Rostock, Institute of Physics

Country

Germany

ORCID For Submitting Author

0000-0002-5132-2961

Declaration of Conflict of Interest

No conflict of interest

Version Notes

Corrected version

Exports