Anti-phase boundaries in platinum-copper-alloy nanoparticles
Proton exchange membrane fuel cells are one of the low-carbon mobility technologies of the future. The use of platinum in catalysts represents a major cost and thus a barrier to wider commercialization of the technology. To reduce the cost of fuel cells and at the same time relieve the pressure on scarce resources of this rare metal, nanoparticles made of platinum alloyed with cheaper transition metals and distributed over a high surface area carbon support are used to catalyze the oxygen reduction reaction. Since the structure of electrocatalysts has a decisive influence on their performance, the relationships between the various aspects of structure and catalytic performance need to be studied in detail.
We prepared nanoparticles from a platinum-copper alloy containing periodic anti-phase boundaries. These are two-dimensional irregularities in the structure that contribute to chemical disorder by interrupting the repetition of the ordered alloy unit cell through space. Their distribution was determined by experimental and simulated X-ray powder diffraction, and their occurrence was monitored in-situ at different temperatures by high-temperature XRD. The structure was confirmed by EXAFS, electron diffraction, and scanning transmission electron microscopy. The performance of differently synthesized electrocatalysts was evaluated by rotating disk electrode measurements, and it was shown that the presence of anti-phase boundaries has no negative effect on the catalytic activity in the oxygen reduction reaction.
This study contributes to a deeper understanding of the structure-property relationships of electrocatalysts for hydrogen fuel cells. The authors of the study are Ana Rebeka Kamšek, Primož Jovanovič, Francisco Ruiz-Zepeda, Goran Dražić, Miran Gaberšček, Marjan Bele and Nejc Hodnik from the Department of Materials Chemistry, Martin Šala from the Department of Analytical Chemistry, Anton Meden from the Faculty of Chemistry and Chemical Technology, University of Ljubljana, and Iztok Arčon from the Jožef Stefan Institute and the University of Nova Gorica. The research paper was published in Materials Today Nano.
Contact: ana.rebeka.kamsek(at)ki.si, nejc.hodnik(at)ki.si