Covalent bonding photosensitizer–catalyst dyads of ruthenium-based complexes designed for enhanced visible-light-driven water oxidation performance
We have successfully prepared two ruthenium-based covalent bonding photosensitizer–catalyst dyads through a simple procedure. 1H NMR spectra of both dyads show that only a single stereoisomer was formed for each dyad. The spectroscopic and electrochemical properties and photocatalytic water oxidation activities of both dyads were investigated in detail. The results indicate that there is negligible electron communication between the photosensitizer and catalyst centers, and each component maintains the desired photophysical and electrochemical properties, which would diminish excited-state electron recombination by facilitating the intramolecular electron transfer. In the presence of excess sacrificial electron acceptor, the dyad with iodide ligand shows a 5.5-fold increase in catalytic performance as compared to its chloro analogue, indicating that the iodide ligand plays an important role during the catalytic cycle. Moreover, compared with the multi-component system, the dyad with iodide ligand exhibits a fourfold increase in catalytic turnover number.
This work was financially supported by the National Natural Science Foundation of China (21603110) and K. C. Wong Magna Fund in Ningbo University. Y. Z. thanks the support from K. C. Wong Education Foundation, Hong Kong.
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