Preparation and characterization of composite catalysts based on mofs and g-c3n4 for energy applications

Χαϊδόγιαννου, Μαριάννα; Chaidogiannou, Marianna

dc.contributor.author	Χαϊδόγιαννου, Μαριάννα	el
dc.contributor.author	Chaidogiannou, Marianna	en
dc.date.accessioned	2025-01-28T11:21:56Z
dc.date.available	2025-01-28T11:21:56Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/60988
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.28684
dc.rights	Default License
dc.subject	Νιτρίδιο του άνθρακα	el
dc.subject	Μεταλλο-οργανικά πλαίσια	el
dc.subject	Νανοσωματίδια	el
dc.subject	Ετεροδομή	el
dc.subject	Αποδόμηση	el
dc.subject	Carbon nitride	en
dc.subject	Metal-organic frameworks	en
dc.subject	Exfoliation	en
dc.subject	Methylene blue	en
dc.subject	Degradation	en
dc.title	Preparation and characterization of composite catalysts based on mofs and g-c3n4 for energy applications	en
heal.type	bachelorThesis
heal.classification	Energy engineering	en
heal.classification	Material engineering	en
heal.language	en
heal.access	campus
heal.recordProvider	ntua	el
heal.publicationDate	2024-07-12
heal.abstract	In recent decades, there has been a rising awareness of the escalating energy needs and environmental issues caused by the use of fossil fuels and dyes used in the industrial community. Therefore, the researchers have been actively exploring breakthroughs and advancements in the field of materials science and engineering to address the challenge of efficient energy conversion and environmental preservation. Specifically, a pivotal role in works has been gaining the water splitting for H2 production, the conversion of CO2 into products with high heat capacity and the degradation of azo dyes. One of the most widespread azo dyes is methylene blue which causes several problems in effluents, including the consumption of Oxygen dissolved in water, the hindering of penetration of light, both required for aquatic life, and the toxic products of anaerobic degradation. Thus, methylene blue decomposition leading to non-toxic products is crucial. For this purpose, novel pure and composite materials with photocatalytic properties have been invented. Carbon nitride (g-C3N4) is a visible light active metal-free polymeric semiconductor with a graphitic layered structure that disposes suitable band structure. Different generation methods have been reported during the last years, such as direct pyrolysis of N-rich precursors, sol-gel methods, chemical vapor deposition, and solvothermal/hydrothermal methods. However, these materials exhibit several constraints and shortcomings regarding their photocatalytic activity, given that the photogenerated charge carriers have high recombination rate. These challenges can be overcome through modifications such as chemical exfoliation, a process that increases the specific surface area through producing ultrathin nanosheets, construction of highly crystalline g-C3N4 to reduce the crystal defects, and doping. For doping, Metal-Organic Frameworks (MOFs) have been widely investigated. Metal-organic frameworks (MOFs) are highly porous crystalline materials that have attracted significant interest due to their large specific surface areas, customizable topologies, and tunable functional sites. The unique features of this material provide it with a competitive advantage for interesting applications. This unique crystalline material is composed of inorganic secondary building units (SBUs), which can be either metal ions or clusters, and organic linkers that are connected by coordination interactions. The existence of several metal complexes can be ascribed to their varied geometries and assembly numbers, which span from 3 to 12. The fabrication methods are solvothermal/hydrothermal method, microwave-assisted method, ultrasonic-assisted method, and other. These two materials, mentioned above, combined with metal or non-metal nanoparticles can construct composite heterojunctions with superior photocatalytic properties. In this work, it was pursued to fabricate g-C3N4-based composites with Bi nanoparticles, TiO2 nanoparticles, and MOF-808. G-C3N4 was fabricated through the thermal polycondensation method putting the precursor into a muffle furnace at 550°C with a heating rate of 5°C/min maintaining this temperature for 2 hours. The precursors used were melamine, urea, and melamine/urea mixture of different mass ratios (70:30, 50:50, and 30:70) to compare the effects of precursor to the photocatalytic performance of g-C3N4. Exfoliation was conducted through the chemical ultrasonic-assisted method. 2.0g of melamine-derived g-C3N4 were mixed with 20mL H2SO4 and stirred at room temperature for about 15.5 hours. The resulting solution was mixed with 200mL distilled water and ultrasonicated for 1.5 hours in 40W and pulser 4s on, 2s off. The product was centrifugated at 4000rpm for 10 minutes. The suspension came up labeled s1.1 and stored. The sediment was mixed with 100mL of distilled water and centrifugated again under the same conditions. The same procedure was conducted till the suspension s1.10. Afterward, 48mL of the suspensions named s1.1, s1.5, and s1.10 sonicated for 1 hour in 20W and pulser 4s on, 2s off with 1mg TiO2, 1mg of MOFs, and 1 mL of Bi solution in order every possible combination of g-C3N4-based composites to be produced. So, 21 catalysts were produced. Characterizations occurred were XRD and IR for bulk g-C3N4, and Zeta Sizer for the suspensions. XRD and IR patterns certified the production of g-C3N4. Zeta Sizer indicated that the last suspensions produced contain smaller particles and the concentration increases by increasing the suspension series. As far as photocatalytic experiments are concerned, 50mL of a solution of methylene blue with 2*10-5 M and 2, 5, or 1 mL of the different catalysts were used. The solutions were exposed to UV-light irradiation for 2 hours and the results for every 15 minutes of exposure were taken using UV-Vis light spectroscopy. The decrease of the characteristic peak of methylene blue at 663 nm was associated with the degradation percentage. The results showed that the best catalyst produced was g-C3N4/MOF as 1mL of the 10th suspensions-derived catalyst led to 95% degradation of methylene blue in 2 hours. Also, satisfying performance exhibited g-C3N4/MOF/TiO2, g-C3N4/Bi/MOF/TiO2 and g-C3N4/TiO2 composite catalysts. Suggestions for further investigation include changing the fabrication method and precursors for bulk g-C3N4, altering the modification method of g-C3N4, using different quantities of doping factors, and research for different applications of the catalysts such as H2 production, and CO2 conversion.	en
heal.advisorName	Αργυρούσης, Χρήστος	el
heal.committeeMemberName	Κόκκορης, Γεώργιος	el
heal.committeeMemberName	Κορδάτος, Κωνσταντίνος	el
heal.committeeMemberName	Αργυρούσης, Χρήστος	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Χημικών Μηχανικών. Τομέας Σύνθεσης και Ανάπτυξης Βιομηχανικών Διαδικασιών (IV). Εργαστήριο Τεχνολογίας Ανόργανων Υλικών	el
heal.academicPublisherID	ntua
heal.numberOfPages	58 σ.	el
heal.fullTextAvailability	false