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Identifier

000449684

Title

Σύνθεση και μελέτη πορφυρινών σε στερεή μορφή για φωτοκαταλυτική παραγωγή υδρογόνου

Alternative Title

Synthesis and studies of porphyrins at solid state for photocatalytic hydrogen production

Author

Ορφανός, Εμμανουήλ Γ.

Thesis advisor

Κουτσολέλος, Αθανάσιος

Reviewer

Αγγαρίδης, Παναγιώτης
Λαδωμένου, Καλλιόπη

Abstract

Hydrogen is considered to be a promising fuel for clean energy production, so it is of great importance to produce and store H2. The replacement of fossil fuels would lead to the solution of the world's energy and environmental problems. One of the most promising strategies for hydrogen production is photocatalytic water splitting, in which hydrogen will be produced from water. The first economic material such as water combined with solar radiation, which yields a great deal of global energy on Earth, could solve the energy crisis. Systems that take advantage of solar radiation to carry out a catalytic process are called photocatalytic The components that the photocatalytic system needs, apart from the substrate, which is water, and the source of radiation, are the existence of a catalyst, as well as a photosensitizer . Finally, the use of a sacrificial electron donor is required, which completes the photocatalytic system. In this work, an extensive study was carried out on the peripheral substitution of porphyrins in meso positions. More specifically, porphyrins with ether, ester, phenyl, fluoro and mesityl groups were synthesized. They were then studied for the amount of hydrogen they could produce as well as the rate. Therefore, a trend was developed to synthesize porphyrins with desirable substitutions to improve photocatalytic hydrogen production In a second phase, it was presented how the morphology of the components of the photocatalytic system can affect their performance. Different forms were created in the same system using the "good-bad" solvent technique. Characterization studies of each structure were carried out (IR, UV, PXRD, SEM).Each form gave different photocatalytic results. With the information gathered from the two previous parts of the work, an attempt was made to simplify the photocatalytic system, reducing the number of necessary components. This was achieved by creating photocatalysts, meaning that one component can have a dual role in catalysis. In the fourth and final part, having knowledge of which forms have the ability to act effectively, we synthesized porphyrins with carboxylic binding groups and developed techniques that would help us achieve the desired structure, resulting in the creation of a system with hydrogen evolution rate equal to 353,9 μmol/g h^-1 in mild conditions.

Language

Greek

Subject

Hydrogen

Photocatalyst

Photosensitizer

Porphyrin

Πορφυρίνη

Στερεά μορφή

Υδρογόνο

Φωτοευαισθητοποιητής

Φωτοκαταλύτης