Institut des Sciences Moléculaires d'Orsay



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Accueil > Équipes scientifiques > Systèmes Moléculaires, Astrophysique et Environnement (SYSTEMAE) > Offres de stages, thèses et post-docs > Competing relaxation processes after a photonic excitation within photosystems produced from natural resources, toward artificial photosynthesis based on molecules

Stage de M2

Competing relaxation processes after a photonic excitation within photosystems produced from natural resources, toward artificial photosynthesis based on molecules

Niveau M2 ou thèse

Artificial photosynthesis aims at building photosystems capable of transforming H2O and CO2 into energy rich molecules such as H2 and CH4 using solar irradiation. In the photosystems, after the photonic excitation, multi-timescale photophysical events are taking place. Among these, electron transfer or electronic energy storage within the photosystems are of primary importance to enable the ignition of the catalytic reactions. However many competing processes contribute to lower the quantum yield of the targeted relaxation channel. Therefore, the understanding of the main physico-chemical properties that influence relaxation pathways toward the most productive one is of crucial importance. We propose to characterize and study photosystems that may be involved in photoreduction of CO2 (CO2RR) toward solar fuels or photodissociation of H2O toward H2 photocatalytic production.
One major challenge for artificial photosynthesis concerns the development of non-toxic, noble metal-free, efficient, selective, and recyclable homogeneous or heterogeneous catalysts. Although a huge effort is performed by chemists to synthetized such systems, natural resources for the different entities composing a photosystem (the photosensitizer and the catalyst for instances) are also of strong interest. Such molecular photocatalysts employing natural resources will also be at the focus during the internship. The use of carotenoids assemblies capable to perform singlet fission, producing two excited states out of one photon are already explored at the Institut de Biologie Intégrative de la Cellule from biological samples and will be further studied during the internship. Several time-resolved spectroscopies will be used to access the dynamics, with a strong effort during the internship on time-resolved and steady-state resonant Raman spectroscopy. The goal will be to explore the photophysical processes in the nanosecond to millisecond range. In the systems employing singlet fission, the organizational parameters of the assembled carotenoids will be investigated. This will allow to understand the optimal configuration to speed up the singlet fission process (doubling the number of excited states) and decoupling of the generated triplets (stabilization of the excited state). At the end of the internship, exploration of the role of the different component of the photosystems, from the photosensitizer to the catalyst, in different conditions and using different spectroscopies will provide a solid photophysical background to the student. In addition, fundamental questions raised by artificial photosynthesis and solar fuels will be questioned.

Please note that the project will be performed under co-supervision with Dr Manuel Llansola-Portoles (I2BC) and Dr Ha-Thi Minh-Huong (ISMO).

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