Francisco Ruiz-Zepeda (Ljubljana / SI), Matija Gatalo (Ljubljana / SI), Mohammed Azeezulla Nazrulla (Ljubljana / SI), Marjan Bele (Ljubljana / SI), Goran Dražić (Ljubljana / SI), Miran Gaberšček (Ljubljana / SI), Nejc Hodnik (Ljubljana / SI)
Abstract text (incl. figure legends and references)
In this work we have studied the thermal annealing process of carbon supported Cu3Pt nanoparticles that can be employed as a cathode material for the oxygen reduction reaction (ORR) in fuel cells [1]. By following the growth mechanism at different temperatures we have been able to observe that there is a Cu enrichment during the heat treatment, since there is a relatively large surplus of CuO needle-like particles from the previously double passivation galvanic displacement step. This process seems to involve the migration of Cu single atoms via the carbon support. At temperatures up to 500 °C, other effects were observed such as particle reshaping as well as ordering of the crystal lattice which is due to the Cu enrichment of the initial Pt-Cu nanoparticles giving as a result the Cu3Pt structure. Heating up till 800 °C, the growth is mainly due to coalescence. Ostwald ripening was apperently not observed to play a significant role in the nanoparticle size. And due to the partial vapor pressure at this temperature Cu loss was experienced. These findings, aside from providing insights into the morphological and structural characteirstics in the alloys (and relating it to the performance as catlaysts), can serve as a framework to stablish equally designed expeimetns for similar Cu related systems.
References
[1] M. Gatalo, F. Ruiz-Zepeda, N. Hodnik, G. Dražić, M. Bele, M. Gaberšček. Insights into thermal annealing of highly-active PtCu3/C Oxygen Reduction Reaction electrocatalyst: An in-situ heating transmission Electron microscopy study. Nano Energy 63 (2019) 103892.
Aknowledgements
Authors would like to thank the European Research Council (ERC) Starting Grant 123STABLE (Grant agreement ID: 852208).