PHOTOCHEMICAL SYSTEM FOR ENERGY CONVERSION
Academic year and teacher
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- Versione italiana
- Academic year
- 2017/2018
- Teacher
- MIRCO NATALI
- Credits
- 6
- Didactic period
- Secondo Periodo Didattico
- SSD
- CHIM/03
Training objectives
- The main objectives of the course include the possibility for the student to acquire knowledge of cutting-edge scientific issues related to the global energy problem and how solar energy can be exploited for a sustainable energy development. In particular the student will learn about the general structure and the functional units of an artificial photosynthetic system devoted to solar energy conversion, the photochemical processes involved, the reaction schemes potentially exploitable and the related mechanism, the spectroscopic and electrochemical techniques that allow for its characterization, and eventually the possible practical applications.
At the end of the course the student will be able to understand and evaluate the structure and the functions of complex photochemical systems devoted to solar energy conversion and their potential applications. Additionally, the student will acquire sufficient notions towards the interpretation of experimental data aiming at their characterization. Prerequisites
- Fundamentals of photochemistry, electrochemistry, inorganic chemistry, physical chemistry.
Course programme
- The course consists of 36 hours frontal lecture in which the following topics will be covered.
Introduction to the global energy problem. Fossil fuels and global warming. General aspects of solar energy conversion.
Natural Photosynthesis: anoxygenic photosynthesis in bacteria and green plants photosynthesis. Conversion of solar energy in natural photosynthetic systems.
Structure of an artificial photosynthetic device. Main thermodynamic and kinetic requirements. Functional units. Candidate reactions and transformations in an artificial photosynthetic system.
Solar light harvesting and artificial photosynthetic antennae. Examples of molecular artificial antennae.
Supramolecular systems for photoinduced charge separation. Photoinduced electron transfer and superexchange mechanism.
Proton-coupled electron-transfer.
Oxidative half-reaction: Water oxidation. Molecular water oxidation catalysts (WOCs). Thermodynamic requirements. Water oxidation mechanism, nucleophilic attack and radical coupling. Metal-oxo intermediate and effect of its electronic nature on the mechanism. Experimental characterization of molecular WOCs. Electrochemical techniques for the study of WOCs. Coupling of the water oxidation reaction with light. Water oxidation photocatalysis. Spectroscopic techniques for studying photocatalytic systems for water oxidation.
Reductive half-reaction: Proton reduction to hydrogen. Molecular hydrogen evolving catalysts (HECs). Hydrogen evolution mechanism. Thermodynamic requirements, metal pKa and hydricity Electrochemical techniques for the study of HECs. Coupling of hydrogen evolution with light and photocatalysis. Spectroscopic techniques for studying photocatalytic systems for hydrogen evolution. Carbon dioxide reduction. Possible reactions. Catalysts for carbon dioxide reduction and their characterization. Photocatalysis.
Integrated systems for solar energy conversion. Dye-sensitized photoelectrochemical cells (DS-PECs). Electronic structure of a semiconductor, intrinsic and extrinsic semiconductors, semiconductor-solution contact. Heterogeneous electron transfer and Gerischer theory. Examples of DS-PECs. Half-cells and tandem cells. Thermodynamic and kinetic limiting factors. Basic characterization of a DS-PEC, figures of merit of a DS-PEC device.
Solar energy conversion into electricity. Photovoltaic devices. Solid-state solar cells, p-n junction, dye-sensitized solar cell (DSSC), perovskite solar cell, bulk heterojunction. Basic characterization of a solar cell and figures of merit. Coupling of photovoltaic devices with electrolytic or electrosynthetic systems for solar energy conversion into fuels.
Other photochemical processes potentially relevant to photoelectrochemical devices. Up-conversion. Singlet fission. Didactic methods
- The course consists of 36 hour frontal lecture covering the topics reported above and will be delivered taking advantage of presentation slides integrated, when needed, by explanation on the blackboard.
Learning assessment procedures
- The aim of the final examination is to ascertain whether the student has acquired the knowledge and abilities reported above. The exam consists of an oral assessment with 3 questions. The student will be allowed to start the discussion from a topic of choice. The exam will be considered passed only if the student has answered correctly and exhaustively to at least 2 questions.
Reference texts
- The presentation slides used by the teacher will be available to all students. Further insights on the topics covered during the course will be in the form of scientific articles, scientific reviews or essays, or book chapters provided by the teacher. Additional contents can be found in:
"Photochemistry and Photophysics, Concepts, Research, Applications" V. Balzani, P. Ceroni, A. Juris, Wiley-VCH,Verlag 2014.
