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Identifier |
000447121 |
Title |
Σύνθεση και χαρακτηρισμός πορφυρινικών παραγώγων για φωτοκαταλυτική παραγωγή υδρογόνου |
Alternative Title |
Synthesis and characterization of porphyrin derivatives, for photocatalytic hydrogen production |
Author
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Αγαπάκη, Ελένη Γ.
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Thesis advisor
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Κουτσολέλος, Αθανάσιος
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Reviewer
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Αγγαρίδης, Παναγιώτης
Μητράκη, Άννα
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Abstract |
Fossil fuels are our primary energy sources; however, their combustion causes climate
change due to the production of greenhouse gases such as carbon dioxide (CO2). One
of the most essential scientific challenges of this century is to reduce the ecological
footprint of human activity targeting a sustainable existence of mankind on the planet.
Among the available renewable energy sources, sunlight is by far the most attractive
candidate, because it is vast, almost inexhaustible and clean. The sun can be used to
produce a promising fuel, hydrogen. Hydrogen is rightly the fuel of the future as
during its combustion the only by-product it produces is water. Photocatalytic
hydrogen (H2) production is considered to be the most promising method of
converting water to hydrogen. To date, a variety of photocatalytic systems for
hydrogen production have been developed. These typically use a photosensitizer (PS)
that absorbs light, a catalyst (CAT) that reduces water to hydrogen, and a sacrificial
electron donor (SED) that regenerates the oxidized photosensitizer (PS+). The purpose
of this master's thesis is the synthesis and study of suitably modified porphyrins that
will maximize the efficiency of the photocatalytic system. Titanium dioxide (TiO2)
after its modification with platinum nanoparticles (Pt nanoparticles) was used as a
catalyst, while in order to increase the photocatalytic production of hydrogen
porphyrin derivatives adsorbed on the surface of TiO2. In the first part of the work, we
examined the impact of: i) the position of the carboxyl group (ortho- or para-position)
and ii) the distance between the porphyrin macrocycle and the anchoring group. It has
been found that due to stereochemical inhibition the ortho adsorption of porphyrins is
impossible. While referring to the the distance between the porphyrin macrocycle and
the anchoring group, it was observed that the zinc porphyrins with a longer carbon
chain give a lower photocatalytic efficiency. In the second part of this dissertation,
porphyrins bearing four carboxyl groups and different metals in the central porphyrin
ring were synthesized. The effect of size of carbon chains and different metals on the
photocatalytic production of hydrogen was studied. In this part, the porphyrins with
the largest carbon chains showed better results while when they were platinum
mineralized, they showed the highest efficiency, achieving 10819 catalytic cycles
(TONs) in just 24 hours of irradiation. The study was extended to find the best system
conditions. After four different sacrificial electron donors (SEDs) and two different
semiconductors, the system was found to have the highest efficiency with Ascorbic
Acid (1 M) pH = 4 and TiO2/Pt (0.5% w/w).
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Language |
Greek |
Subject |
Carboxyl groups |
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Energy/electron transfer |
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Photocatalysis |
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Platinum nanoparticles |
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TiO2/Pt |
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Titanium dioxide |
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Διοξείδιο του τιτανίου |
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Καρβοξυλομάδες |
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Μεταφορά ενέργειας / ηλεκτρονίων |
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Νανοσωματίδια πλατίνας |
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Πορφυρίνες |
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Φωτοκατάλυση |
Issue date |
2022-03-31 |
Collection
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School/Department--School of Sciences and Engineering--Department of Chemistry--Post-graduate theses
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Type of Work--Post-graduate theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/5/9/a/metadata-dlib-1648449692-179773-20971.tkl
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Views |
494 |
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