doctoral dissertation
Peter Majerič (Avtor), Rebeka Rudolf (Mentor), Bernd Friedrich (Mentor)

Povzetek

Doktorsko delo predstavlja študije, eksperimentalno delo, tehnike karakterizacije, rezultate in analize, s katerimi je povezana sinteza čistih, okroglih, neaglomeriranih nanodelcev zlata (AuNPs) z velikostjo okoli 50 nm. V prvem delu raziskav smo sintetizirali AuNPs s konvencionalno ultrazvočno razpršilno pirolizo (USP). Za surovino smo uporabili tetrakloroaurično kislino HAuCl4(s), ki smo jo raztopili v vodi. To raztopino smo v komori z ultrazvokom razpršili v kapljice, ki jih je nosilni plin N2 prenesel v reakcijsko peč. V tej peči so potekale stopnje sinteze: izhlapevanje kapljic, toplotna dekompozicija, redukcija s plinom H2 in zgoščevanje. Nastali so AuNPs različnih oblik z velikostmi do 300 nm, pri čemer smo identificirali visoko stopnjo aglomeracije. Ker s konvencionalnim USP nismo dosegli cilja, smo postavili hipotezo, da lahko izdelamo ciljne AuNPs z modificiranim USP, kjer je cona izhlapevanja kapljic ločena od reakcijske peči, reducirni plin pa je uveden neposredno v reakcijsko peč. Za potrditev hipoteze smo z eksperimenti preučevali vplivne parametre USP-sinteze: koncentracijo Au v začetni raztopini, temperature v coni izhlapevanja kapljic in v reakcijski peči ter pretok plinov N2 in H2. S pomočjo tehnik karakterizacij (TEM, DLS, ICP) na nastalih AuNPs smo ugotovili, da pri USP-sintezi hkrati potekata dva mehanizma nastanka nanodelcev (»kapljica-v-delec«, DTP in »plin-v-delec«, GTP). Z DTP nastajajo veliki nanodelci – do 300 nm, z GTP pa majhni – do 50 nm. Kadar potekata oba mehanizma hkrati, dobimo neugodno bimodalno velikostno porazdelitev AuNPs. Na tej osnovi smo postavili model nastanka AuNPs, ki pojasnjuje, kako lahko pri USP-sintezi s spreminjanjem koncentracije Au v začetni raztopini in pretokov plinov vplivamo na DTP in GTP mehanizma nastanka v korist GTP. S ciljno izbranimi parametri (0,5 g/l Au, 4,5 l/min N2, 2,0 l/min H2) smo ustvarili pogoje za nastanek AuNPs z GTP-mehanizmom. Pri tem so nastali okrogli AuNPs z ozko velikostno porazdelitvijo (37,0 ± 5,5 nm). Tako smo potrdili pravilnost postavljenega modela in hipotezo, da lahko z modificiranim USP izdelamo AuNPs ciljnih lastnosti.

Ključne besede

modified Ultrasonic Spray Pyrolisis;gold nanoparticles;formation mechanism;separate evaporation;

Podatki

Jezik: Angleški jezik
Leto izida:
Tipologija: 2.08 - Doktorska disertacija
Organizacija: UM FS - Fakulteta za strojništvo
Založnik: P. Majerič]
UDK: 669.21.091:[544.57:66.092-97](043.3)
COBISS: 19609622 Povezava se bo odprla v novem oknu
Št. ogledov: 1521
Št. prenosov: 118
Ocena: 0 (0 glasov)
Metapodatki: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Ostali podatki

Sekundarni jezik: Slovenski jezik
Sekundarni naslov: Sinteza nanodelcev zlata z modificirano ultrazvočno razpršilno pirolizo
Sekundarni povzetek: This Doctoral Dissertation presents the studies, experimental work, characterization techniques, results and analyses of synthesis of very pure, spherical, unagglomerated gold nanoparticles (AuNPs), with sizes around 50 nm. In the first part of the research, the AuNPs were synthesized with conventional Ultrasonic Spray Pyrolysis (USP). For the raw material, tetrachloroauric acid HAuCl4(s) was dissolved in water. This precursor solution was then sprayed into droplets with ultrasound, and a carrier gas N2 then transported the droplets into a reaction furnace. In this furnace the AuNP synthesis stages took place: Droplet evaporation, thermal decomposition, reduction with H2 gas and densification. The resulting AuNPs had diverse shapes in sizes up to 300 nm, with a high degree of agglomeration. Because the aim was not achieved with the conventional USP, a hypothesis was proposed where the targeted AuNPs could be synthesized with a modified USP. With this modification, the droplet evaporation zone is separated from the reaction furnace and the reduction gas is introduced directly into the reaction furnace. To confirm this hypothesis we have carried out experiments in order to determine the influential parameters of USP synthesis: The concentration of Au in the precursor solution, evaporation zone temperature, reaction furnace temperature and gas flows of N2 and H2. Characterization of the obtained AuNPs has shown that 2 formation mechanisms take place in USP synthesis (Droplet-to-Particle, DTP and Gas-to-Particle, GTP). With DTP, nanoparticles up to 300 nm are formed, while smaller nanoparticles up to 50 nm are formed with GTP. When both mechanisms occur simultaneously, we obtain a bimodal size distribution of AuNPs. Based on these findings, we have set up an AuNP formation model, explaining how one can control the DTP and GTP mechanisms in USP by changing the most influential parameters, the concentration of Au in the precursor solution and the gas flows. Based on this model, parameter values were selected (0.5 g/l Au, 4.5 l/min N2, 2.0 l/min H2) to establish conditions where the AuNPs are formed only by the GTP mechanism. This has yielded spherical AuNPs in a narrow size distribution (37.0 ± 5.5 nm). Targeted AuNPs were thus synthesized, confirming the model and the hypothesis of AuNP synthesis with USP.
Sekundarne ključne besede: modificirana ultrazvočna razpršilna piroliza;nanodelci zlata;mehanizmi nastanka;karakterizacija;doktorske disertacije;
URN: URN:SI:UM:
Vrsta dela (COBISS): Doktorska disertacija
Komentar na gradivo: Univ. of Maribor, Faculty of Mechanical Engineering
Strani: X, 95 str.
ID: 9141110