[SCAN] Interfacing biomolecules with electrode materials: Towards semi-artificial photosynthesis

Title: Interfacing biomolecules with electrode materials: Towards semi-artificial photosynthesis

Speaker: Felipe Conzuelo

Abstract: Oxygenic photosynthesis is perhaps one of the most important natural processes sustaining life on earth through the production of molecular oxygen and the assimilation of carbon dioxide into organic matter. The process is driven by the absorption of sunlight as the primary energy source and relies on two sequential photo¬induced charge separation steps performed by the membrane-protein complexes known as photosystem I (PSI) and photosystem II (PSII). The unique properties, high quantum yield, and considerable abundance of the photosynthetic protein complexes have driven considerable interest for coupling of these biomolecules with electrode materials for the development of semi-artificial biodevices that will enable the conversion of solar light energy into electrical power as well as the synthesis of valuable products. In particular, PSI is of great interest as a building block for the fabrication of bio-hybrid solar energy conversion devices. Resembling a photodiode, PSI is able to pump electrons to a high energy level upon absorption of visible light. After subsequent internal electron transfer, a relatively long-lived state is obtained consisting of two redox centers of opposite charge with a potential difference of about one volt. Recovery of the remarkably large charge separation in PSI is required to achieve high-energy conversion efficiencies. Therefore, for the fabrication of PSI-based bioelectrodes, numerous redox mediators with potentials adjusted to the terminal redox sites at PSI have been proposed as artificial charge carriers. However, the design of bio-hybrid solar energy conversion devices involves several challenges. The large voltage difference between the terminal redox sites at PSI translates into a substantial driving force for short-circuiting processes. As a result, at least part of the generated photocurrent is canceled out in conventionally implemented devices. Therefore, a better understanding of charge recombination pathways and the electron transfer processes involved in this kind of bioelectrodes is required for the development of highly efficient systems able to provide a unidirectional electron flow. Different approaches for interfacing biomaterials with electrodes are introduced, allowing a detailed study of photo-electrochemical processes and further development of advanced bio-solar cells and bio-photovoltaic devices.

https://us06web.zoom.us/j/84414201190