Universiteit Leiden

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MCBIM Colloquium: Proton-Coupled Electron Transfer in Artificial Photosynthesis

Tuesday 13 February 2024
Gorlaeus Building
Einsteinweg 55
2333 CC Leiden


Photosynthetic conversion of solar energy to a fuel involves a series of photo-induced charge separation steps that lead up to proton-coupled electron transfer (PCET) reactions at the catalysts for water oxidation (oxygen-evolving complex) and fuel formation (Calvin cycle). PCET is involved already in the primary steps of charge separation in the reaction centres, however, and is crucial for the coupling of electron transport to proton translocation across the photosynthetic membrane. 

In artificial photosynthesis, PCET is involved in a similar manner. PCET is required for levelling the potentials of the sequential catalyst redox steps. It also has substantial impact on the reaction rate, due to modulations of the reaction energy barrier as well as the strong dependence on the distance the proton has to tunnel during the reaction. For the design of efficient solar fuels production, and understanding of biological PCET, it is therefore necessary to understand and control PCET reactions.

We have experimentally investigated the mechanism of PCET in model systems, and the conditions that allow for a switch between consecutive and concerted pathways.1 
We have in particular investigated the free-energy dependence of the PCET rate constant and – in collaboration with Profs James Mayer and Sharon Hammes-Schiffer – demonstrated the first example of inverted region behavior.2 
We also discovered the first example of proton-coupled energy transfer (PCEnT), which is a new elementary reaction.3 


  1. R. Tyburski, T. Liu, S.D. Glover, L. Hammarström, J. Am. Chem Soc., 2021, 143, 560-576.
  2. G.A. Parada, Z.K. Goldsmith, S. Kolmar, B. Pettersson Rimgard, B.Q. Mercado, L. Hammarström, S. Hammes-Schiffer, J.M. Mayer, Science, 2019, 364, 471–475.
  3. B. Pettersson Rimgard, Z. Tao, G.A. Parada, L.F. Cotter, S. Hammes-Schiffer, J.M. Mayer, L. Hammarström, Science, 2022, 377, 742-747.
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