Pt / Pt3Y Fuel Cell Nanoparticle Catalyst Fabrication via Sputter Deposition onto Liquid Substrates
Typ
Examensarbete för masterexamen
Program
Publicerad
2020
Författare
Pfeiffer, Robin
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
This thesis presents an overview on the fabrication of Pt and Pt3Y nanoparticles via sput-tering onto liquid substrates for potential use as catalyst of the oxygen reduction reaction in modern fuel cells. It is shown that spherical nanoparticles with diameters in the range of 1 – 4 nm can be formed by sputtering onto different liquids. Ionic liquids as well as polyethylene glycol proved to be suitable substrates for Pt nanoparticles. However, Pt3Y reacted with ionic liquids to form undesirable structures and compounds. Sputtering of Pt3Y onto polyethylene glycol resulted in the formation of nanoparticles without any un-wanted reactions. Compared to an ionic liquid substrate, polyethylene glycol produced nanoparticles with a slightly broader particle size distribution due to less effective stabi-lization mechanisms. Summarized, the liquid polymer turned out to be the best liquid sub-strate candidate for the formation of Pt3Y nanoparticles.
The size of the nanoparticles varied slightly with the applied liquid substrate without ex-hibiting significant trends. Furthermore, the size increased by roughly 20 – 30% by means of a post heat-treatment at 165 °C. An elevated sputtering power resulted in larger parti-cle sizes but an unchanged particle concentration, which points out a particle formation and growth mechanism at the liquid surface. This suggestion could be validated by an in-vestigation of the visual appearance of the sputtered wafers. The nanoparticles fabricated in polyethylene glycol exhibited an electrocatalytic activity for the oxygen reduction reac-tion in an acidic environment in rotating disc electrode measurements. Alloying the na-noparticles with Y led to an activity enhanced by a factor of 1.67 compared to pure Pt nanoparticles. This proves the particles’ potential application in fuel cells and provides motivation for further research on this topic.
Beskrivning
Ämne/nyckelord
fuel cell , catalysis , nanoparticles , platinum , yttrium , sputter deposition , liquid substrate , ionic liquid , polyethylene glycol