Light driven water oxidation is a key step in artificial photosynthesis, aimed at splitting water into hydrogen and oxygen with sunlight. In such process, the interactions between a photosensitizer (PS) and a water oxidation catalyst (WOC) play a crucial role in the rates of photoinduced electron transfers, determining the overall quantum efficiency of the system. In this work, by means of Small Angle X-ray Scattering (SAXS) we investigate the nature of the aggregates between ruthenium polypyridine photosensitizers (Rubpy and Ru4dend) and a tetraruthenium polyoxometalate (Ru4POM) water oxidation catalyst. Aggregate scattering is confirmed by the strong intensity-increase in the low-q regime, whereas the power law-fit of this region show slopes between 3 and 4, suggesting globular and porous aggregates. Intermolecular PS/WOC distances lower than 3 nm support the observed fast photoinduced electron transfers (<120 ps), however the proximity of the two components in the hybrids is also responsible for fast charge recombination. Approaches for inhibiting such undesired process are discussed.
Ruthenium based photosensitizer/catalyst supramolecular architectures in light driven water oxidation
LA GANGA, GIUSEPPINA;PUNTORIERO, Fausto;CAMPAGNA, Sebastiano
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2017-01-01
Abstract
Light driven water oxidation is a key step in artificial photosynthesis, aimed at splitting water into hydrogen and oxygen with sunlight. In such process, the interactions between a photosensitizer (PS) and a water oxidation catalyst (WOC) play a crucial role in the rates of photoinduced electron transfers, determining the overall quantum efficiency of the system. In this work, by means of Small Angle X-ray Scattering (SAXS) we investigate the nature of the aggregates between ruthenium polypyridine photosensitizers (Rubpy and Ru4dend) and a tetraruthenium polyoxometalate (Ru4POM) water oxidation catalyst. Aggregate scattering is confirmed by the strong intensity-increase in the low-q regime, whereas the power law-fit of this region show slopes between 3 and 4, suggesting globular and porous aggregates. Intermolecular PS/WOC distances lower than 3 nm support the observed fast photoinduced electron transfers (<120 ps), however the proximity of the two components in the hybrids is also responsible for fast charge recombination. Approaches for inhibiting such undesired process are discussed.File | Dimensione | Formato | |
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