Abstract
The molecular apparatus behind biological photosynthesis retains its long-term functionality through enzymatic repair. However, bioinspired molecular devices designed for artificial photosynthesis, consisting of a photocentre, a bridging ligand and a catalytic centre, can become unstable and break down when their individual modules are structurally compromised, halting their overall functionality and operation. Here we report the active repair of such an artificial photosynthetic molecular device, leading to complete recovery of catalytic activity. We have identified the hydrogenation of the bridging ligand, which inhibits the light-driven electron transfer between the photocentre and catalytic centre, as the deactivation mechanism. As a means of repair, we used the light-driven generation of singlet oxygen, catalysed by the photocentre, to enable the oxidative dehydrogenation of the bridging unit, which leads to the restoration of photocatalytic hydrogen formation.

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Data availability
Source data are provided with this paper and can also be found via Zenodo (https://doi.org/10.5281/zenodo.5565021). All other data supporting the findings of this study are available within the paper and its Supplementary Information files.
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Acknowledgements
We thank the German Science Foundation for funding via the TRR 234 CataLight (project number 364549901; project A1, C.M., B.D.-I. and S.R.; project B4, M.W.; project C5, P.S., S.K. and S.G), the Fonds der Chemischen Industrie (Kekulé-Stipendium, C.M.) and the Studienstiftung des Deutschen Volkes (PhD scholarship, B.B.). We acknowledge the developers of the KiMoPack software employed for global lifetime analysis of the time-resolved spectra. All calculations were performed at the Universitätsrechenzentrum (Friedrich Schiller University Jena, P.S., S.K. and S.G.). The funding organizations had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.
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M.G.P., E.T.E.K. and D.C. performed the catalysis experiments, C.M. performed the steady-state and time-dependent in situ spectroscopic studies, and M.S. and M.W. synthesized and investigated the hydrogenated photocatalyst. M.G.P., A.K.M., B.B., S.F., J.H., D.C., F.L., G.S.H. and S.R. developed the active repair strategies. P.S., S.K. and S.G. conducted the quantum chemical simulations. M.G.P, C.M., L.P., G.S.H., J.G.V., A.K.M., B.D.-I. and S.R. wrote the manuscript with help from all the other authors.
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Supplementary Figs. 1–27, Tables 1–4, Discussion and Experimental Details.
Source data
Source Data Fig. 1
Hydrogen turnover numbers and chemical structures.
Source Data Fig. 2
In situ absorption data and chemical structures.
Source Data Fig. 3
In situ absorption and ultrafast transient absorption data, hydrogen turnover numbers (mean, s.d., n = 3) and peak area ratios.
Source Data Fig. 4
Absorption data.
Source Data Fig. 5
Hydrogen turnover numbers and chemical structures.
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Pfeffer, M.G., Müller, C., Kastl, E.T.E. et al. Active repair of a dinuclear photocatalyst for visible-light-driven hydrogen production. Nat. Chem. 14, 500–506 (2022). https://doi.org/10.1038/s41557-021-00860-6
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DOI: https://doi.org/10.1038/s41557-021-00860-6
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