Photocatalysis and Its applications

Fragkos, Georgios; Φράγκος, Γεώργιος

dc.contributor.author	Fragkos, Georgios	en
dc.contributor.author	Φράγκος, Γεώργιος	el
dc.date.accessioned	2026-02-09T10:58:41Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/63363
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.31058
dc.rights	Default License
dc.subject	Photocatalysis	en
dc.subject	Methylene Blue	en
dc.subject	Dye Degradation	en
dc.subject	Plasmonic	en
dc.subject	Φωτοκατάλυση	el
dc.subject	Μπλε του Μεθυλενίου	el
dc.subject	Διάσπαση ρύπων	el
dc.subject	Πλασμονικό	el
dc.subject	Heterojunction photocatalysts	en
dc.subject	Φωτοκαταλυτική ετεροεπαφή	el
dc.title	Photocatalysis and Its applications	en
heal.type	masterThesis
heal.classification	Photocatalysis	en
heal.dateAvailable	2027-02-08T22:00:00Z
heal.language	en
heal.access	embargo
heal.recordProvider	ntua	el
heal.publicationDate	2025-06-26
heal.abstract	The increasing energy demands as well as the extensive pollution of the atmosphere and the environment in general are some of the most important problems which humanity faces. In particular, the excessive consumption of fossil fuels has turned the attention of scientists to alternative ways of producing energy, which are at the same time more environmentally friendly. Hydrogen represents a highly promising energy solution for multiple industrial fields alongside other sectors since it offers eco-friendly production methods. The ongoing energy crisis generates problems as does the high accumulation of carbon dioxide within the atmosphere. Atmospheric pollution by carbon dioxide is a product of the rapid industrial and technological development of the last two centuries and comes mainly from the combustion of fossil fuels. Furthermore, there is ongoing concern with the rise in industrial liquid pollutants contaminating water sources, creating an immediate hazard to flora-fauna on earth. One of these substances is methylene blue, a dye that comes from the clothing industry. In an effort to tackle this issues, scientists have turned their attention photocatalysis. Photocatalysis is a method utilized in water splitting, to reduce carbon dioxide into less toxic carbon-based compounds, and to break down pollutants. All the extensive research that has been conducted in the area of photocatalysis has led to the synthesis of various semiconductors, such as metal oxides, as potential photocatalysts. The most prevalent issue that afflicts these semiconductors is the excessive recombination rates of electrons and holes, which limits the photocatalytic activity of the material. To solve this problem, nanocomposite semiconductor materials have been developed, thus creating semiconductor heterojunctions. The photocatalytic activity of such heterojunctions is also improved by the incorporation of graphitic structure materials and noble metals. In the context of this thesis, a study of photocatalysis was made for the decomposition of methylene blue. For this purpose, nanocomposite materials based on tungsten trioxide (WO_3) and barium titanate (BaTiO_3) were manufactured by two different methods: with the help of an autoclave (marked as (A)) and by calcinating the oxides at a temperature of 700℃ (marked as (B)). After the connection of the metal oxides graphite nitride (g-C_3 N_4) was added to these materials. The addition of g-C_3 N_4 aims to create a substrate, which presents a graphitic structure and helps in the uniform dispersion of the material nanoparticles, while increasing the recombination time of the carriers. Finally, silver (Ag) particles were added to the nanocomposite in order to increase the photocatalytic activity of the materials through the LSPR mechanism, which semiconductor materials exhibit when they are connected to nobel metals, and increases the recombination time of the carriers. It is noted that the method followed for connection of the metal oxides with the g-C_3 N_4 and Ag is the same in both cases, in order to enable comparison of the photocatalysis results of the two nanocomposites made with different methods. For the study of methylene blue decomposition, photocatalysis was performed for the materials WO_3/BaTiO_3 (A), g-C_3 N_4/WO_3/BaTiO_3 (A), g-C_3 N_4/WO_3/BaTiO_3/Ag(A), g-C_3 N_4/WO_3/BaTiO_3 (B) and g-C_3 N_4/WO_3/BaTiO_3/Ag(B). The measurements taken were methylene blue absorption measurements at the characteristic peak of its wavelength (λ=664nm). In order to make a comparison between the photocatalysts, measurements were performed at 1 hour (dark conditions), at 2, 3, 4 hours and at 24 hours for each photocatalysis. From these measurements, the experimental results were processed. Finally, as can be seen from the comparison of the experimental results, the method of producing a nanocomposite by autoclave shows improved results compared to the method of producing a nanocomposite by calcination. As observed, the photocatalytic capacity of the nanocomposite is enhanced by the addition of g-C_3 N_4 and was enhanced even more by the addition of Ag. Taking into account the measurements in dark conditions, overall it is observed that the nanocomposite materials g-C_3 N_4/WO_3/BaTiO_3 (A) and g-C_3 N_4/WO_3/BaTiO_3 (Β) show a greater degree of MB decomposition compared to the materials g-C_3 N_4/WO_3/BaTiO_3/Ag(Α) and g-C_3 N_4/WO_3/BaTiO_3/Ag(B).	en
heal.advisorName	Hristoforou, Evangelos	el
heal.committeeMemberName	Kollia, Constantina	en
heal.committeeMemberName	Argirusis, Christos	en
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Ηλεκτρολόγων Μηχανικών και Μηχανικών Υπολογιστών	el
heal.academicPublisherID	ntua
heal.numberOfPages	70 σ.	el
heal.fullTextAvailability	false