Razvoj nanoplazmonskih materialov za uporabo v procesih heterogene fotokatalize : doktorska disertacija

Slapničar, Špela

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Title:	Razvoj nanoplazmonskih materialov za uporabo v procesih heterogene fotokatalize : doktorska disertacija
Authors:	ID Slapničar, Špela (Author) ID Pintar, Albin (Mentor) More about this mentor...
Files:	DOK_Slapnicar_Spela_2025.pdf (9,52 MB) MD5: 805D2D1B3293E7D095DE4143F6D96423
Language:	Slovenian
Work type:	Doctoral dissertation
Typology:	2.08 - Doctoral Dissertation
Organization:	FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:	Titanov dioksid (TiO2) je dobro uveljavljen fotokatalitski material, zlasti na področju čiščenja vode in zraka. V doktorski disertaciji smo se zato osredotočili na razvoj in optimizacijo plazmonskih fotokatalizatorjev na TiO2 nosilnem fotokatalizatorju, za učinkovito fotokatalitsko razgradnjo onesnažil. Posebno pozornost smo namenili vplivu sinteznih parametrov, morfologiji nosilnega katalizatorja TiO2 ter velikosti, obliki in vrsti plazmonskih kovin na fotokatalitsko aktivnost materialov. Cilj obsežne in sistematične raziskave je bil prispevati k boljšemu razumevanju ključnih dejavnikov, ki vplivajo na lastnosti katalizatorjev ter tako pospešiti razvoj naprednih fotokatalizatorjev za okoljske aplikacije. V prvem delu raziskav smo se osredotočili na znane Au+TiO2 katalizatorje s tehniko mokre impregnacije, pri čemer smo spreminjali medij (voda ali etanol), čas mešanja in končno temperaturo sinteze. Rezultati so pokazali, da ti parametri močno vplivajo na velikost Au nanodelcev ter posledično na fotokatalitsko aktivnost materialov. Zlati nanodelci so imeli najmanjši premer, ko je mešanje v etanolu potekalo dalj časa, s končnim korakom kalcinacije. Ta vzorec je imel tudi najvišjo generacijo nosilcev naboja in najučinkovitejšo razgradnjo bisfenola A (BPA), kar potrjuje pomemben vpliv sinteznih parametrov na končne lastnosti katalizatorja. Nadalje smo raziskali vpliv morfologije nosilnega materiala na fotokatalitske lastnosti. Pripravili smo TiO2 v obliki nanopalic (TNR) in nanodelcev (TNP) ter nanje nanesli Au nanodelce. Rezultati so pokazali, da različne morfologije vplivajo na optoelektronske lastnosti materiala. Katalizator TNP+Au je izkazoval večjo sposobnost generacije O2•- radikalov kot TNR+Au, kar je posledica različnih višin Schottkyjeve bariere. Ugotovili smo, da pri razgradnji BPA s TNR+Au ne sodelujejo O2•- radikali, temveč se proces odvija preko interakcije elektronov z molekulami BPA, kar poudarja pomembnost optimizacije Schottkyjeve bariere pri načrtovanju katalizatorjev ter poznavanje mehanizma degradacije onesnažil. Za raziskavo vpliva morfologije kovine smo preučevali sintezo in karakterizacijo katalizatorjev z morfološko bogatimi delci Au na površini TiO2. Z uravnavanjem količine Na-citrata smo uspeli optimizirati tvorbo pravilno oblikovanih Au nanocvetov. Vzorce smo uporabili za testiranje fotokatalitske aktivnosti pri zmanjšanju NO2 pod vidno svetlobo. Vzorec TNR+NF(0.7) z najbolj definiranimi nanocvetovi se je izkazal z visoko fotokatalitsko aktivnostjo, kar je posledica izrazitega plazmonskega efekta na robovih nanocvetov. Katalizator TNR+NF(1.4) ni pokazal te aktivnosti, kar je pripisano deformiranim nanocvetom in ogljikovim specijam iz Na-citrata. Pri segrevanju na 300 °C so se nanocvetovi spremenili v sferične delce Au, ki niso pokazali fotokatalitske aktivnosti, kar poudarja pomen oblike plazmonske kovine. V zaključnem delu smo se osredotočili na raziskavo vpliva različnih plazmonskih kovin (Au, Ag, Pt) na lastnosti katalizatorja. Raziskava je pokazala, da izbira plazmonske kovine močno vpliva na učinkovitost prenosa naboja in posledično na aktivnost katalizatorja. Največjo fotokatalitsko aktivnost je izkazoval katalizator TNR-Pt, ki je imel najmanjše nanodelce in najbolj ugodno porazdelitev energijskih pasov. Poskusi razgradnje BPA so potrdili, da so O2•- radikali ključni pri oksidacijskih reakcijah, kjer je bil vzorec TNR-Pt najučinkovitejši. Celovita karakterizacija sintetiziranih materialov je zagotovila dragocen vpogled na vpliv sinteznih parametrov, morfologije nosilcev, velikosti nanodelcev in izbire plazmonske kovine na fotokatalitsko aktivnost.
Keywords:	onesnaženost okolja, heterogena fotokataliza, TiO2, plazmonske kovine, reaktivne kisikove specije
Place of publishing:	Maribor
Place of performance:	Maribor
Publisher:	[Š. Slapničar]
Year of publishing:	2025
Number of pages:	XVI, 146 str.
PID:	20.500.12556/DKUM-92823
UDC:	544.526:549.514.6(043.3)
COBISS.SI-ID:	258332163
Publication date in DKUM:	20.11.2025
Views:	178
Downloads:	40
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Categories:	KTFMB - FKKT
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Licences

License:	CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International

Link:	http://creativecommons.org/licenses/by-nc-nd/4.0/
Description:	The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:	16.05.2025

Secondary language

Language:	English
Title:	Development of nanoplasmonic materials for use in heterogeneous photocatalytic processes
Abstract:	Titanium dioxide (TiO2) is a well-established photocatalytic material, especially in the fields of water and air purification. In this dissertation, we focused on the development and optimization of plasmonic photocatalysts based on TiO2-supported systems for the efficient photocatalytic degradation of pollutants. Particular attention was paid to the influence of the synthesis parameters, the morphology of the TiO2 carrier and the size, shape and type of plasmonic metals on the photocatalytic activity of the materials. The aim of this comprehensive and systematic research was to contribute to a deeper understanding of the key factors influencing catalyst properties and thus accelerate the development of advanced photocatalysts for environmental applications. In the first part of the study, we investigated known Au+TiO2 catalysts prepared by the wet impregnation technique, varying the solvent (water or ethanol), the mixing time and the final temperature of the synthesis. The results showed that these parameters significantly affect the size of the Au nanoparticles and consequently the photocatalytic performance of the materials. The smallest Au nanoparticles and the most efficient degradation of bisphenol A (BPA) were obtained using ethanol as a solvent with prolonged mixing and a final calcination step. This sample also exhibited the highest charge generation, confirming the significant influence of the synthesis parameters on the final catalyst properties. Next, we investigated the influence of the morphology of the support on the photocatalytic properties. TiO2 was synthesized in the form of nanorods (TNR) and nanoparticles (TNP), followed by the deposition of Au nanoparticles. The results showed that different morphologies influence the optoelectronic properties of the materials. The TNP+Au catalyst showed a greater ability to generate O2•- radicals than TNR+Au, which was attributed to differences in Schottky barrier height. We found that BPA degradation with TNR+Au did not involve O2•- radicals; instead, the process proceeded through the interaction of electrons with BPA molecules, highlighting the importance of optimizing the Schottky barrier and understanding contaminant degradation mechanisms. To investigate the influence of metal morphology, we synthesized and characterized catalysts with morphologically rich Au particles (nanoflowers) on the surface of TiO2. By adjusting the amount of sodium citrate, we were able to successfully optimize the formation of well-defined Au nanoflowers. These samples were tested for photocatalytic NO2 reduction under visible light. The TNR+NF(0.7) sample with the most pronounced nanoflowers showed high photocatalytic activity due to strong plasmonic effects at the edges of the nanoflowers. In contrast, the TNR+NF(1.4) catalyst showed no activity, which was attributed to the deformed nanoflowers and the presence of carbon species from sodium citrate. When heated to 300 °C, the nanoflowers turned into spherical Au particles, which showed no photocatalytic activity, emphasizing the importance of the plasmonic metal morphology. In the last part of the research, we focused on investigating the effects of different plasmonic metals (Au, Ag, Pt) on the catalyst properties. The study showed that the choice of plasmonic metal strongly influences the efficiency of charge transfer and thus the activity of the catalyst. The TNR-Pt catalyst showed the highest photocatalytic activity as it had the smallest nanoparticles and the most favorable energy band alignment. BPA degradation tests confirmed that O2•- radicals play a crucial role in oxidative reactions, with TNR-Pt being the most effective sample. The comprehensive characterization of the synthesized materials provided valuable insights into how the synthesis parameters, the morphology of the support, the size of the nanoparticles and the choice of plasmonic metals influence the photocatalytic activity.
Keywords:	environmental pollution, heterogeneous photocatalysis, TiO2, plasmonic metals, reactive oxygen species

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