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Photochemistry and Electron Transfer Kinetics in a Photocatalyst Model Assessed by Marcus Theory and Quantum Dynamics

Koch A, Kinzel D, Droege F, Gräfe S, Kupfer S (2017)

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Publication Type: Journal article

Publication year: 2017

Journal

Book Volume: 121

Pages Range: 16066-16078

Journal Issue: 30

DOI: 10.1021/acs.jpcc.7b02812

Abstract

The present computational study aims at unraveling the competitive photoinduced electron transfer (ET) kinetics in a supramolecular photocatalyst model. Detailed understanding of the fundamental processes is essential for the design of novel photocatalysts in the scope of solar energy conversion that allows unidirectional ET from a light-harvesting photosensitizer to the catalytically active site. Thus, the photophysics and the photochemistry of the bimetallic complex RuCo, [(bpy)2Ru^II(tpphz)Co^III(bpy)2]⁵⁺, where excitation of the ruthenium(II) moiety leads to an ET to the cobalt(III), were investigated by quantum chemical and quantum dynamical methods. Time-dependent density functional theory (TDDFT) allowed us to determine the bright singlet excitations as well as to identify the triplet states involved in the photoexcited relaxation cascades associated with charge-separation (CS) and charge-recombination (CR) processes. Diabatic potential energy surfaces were constructed for selected pairs of donor-acceptor states leading to CS and CR along linear interpolated Cartesian coordinates to study the intramolecular ET via Marcus theory, a semiempirical expression neglecting an explicit description of the potential couplings and quantum dynamics (QD). Both Marcus theory and QD predict very similar rate constants of 1.55 × 10¹² - 2.24 × 10¹³ s^-1 and 1.21 × 10¹³-7.59 × 10¹³ s^-1 for CS processes, respectively. ET rates obtained by the semiempirical expression are underestimated by several orders of magnitude; thus, an explicit consideration of electronic coupling is essential to describe intramolecular ET processes in RuCo.

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How to cite

APA:

Koch, A., Kinzel, D., Droege, F., Gräfe, S., & Kupfer, S. (2017). Photochemistry and Electron Transfer Kinetics in a Photocatalyst Model Assessed by Marcus Theory and Quantum Dynamics. Journal of Physical Chemistry C, 121(30), 16066-16078. https://doi.org/10.1021/acs.jpcc.7b02812

MLA:

Koch, Alexander, et al. "Photochemistry and Electron Transfer Kinetics in a Photocatalyst Model Assessed by Marcus Theory and Quantum Dynamics." Journal of Physical Chemistry C 121.30 (2017): 16066-16078.

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