Tuning the activity of Pt alloy electrocatalysts by means of the lanthanide contraction

• Autores: María Escudero Escribano, Paolo Malacrida, Martin H. Hansen, Ulrik G. Vej Hansen
• Localización: Science, ISSN 0036-8075, Vol. 352, Nº 6281, 2016, págs. 73-76
• Idioma: inglés
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• Resumen

  • The high platinum loadings required to compensate for the slow kinetics of the oxygen reduction reaction (ORR) impede the widespread uptake of low-temperature fuel cells in automotive vehicles. We have studied the ORR on eight platinum (Pt)–lanthanide and Pt-alkaline earth electrodes, Pt5M, where M is lanthanum, cerium, samarium, gadolinium, terbium, dysprosium, thulium, or calcium. The materials are among the most active polycrystalline Pt-based catalysts reported, presenting activity enhancement by a factor of 3 to 6 over Pt. The active phase consists of a Pt overlayer formed by acid leaching. The ORR activity versus the bulk lattice parameter follows a high peaked “volcano” relation. We demonstrate how the lanthanide contraction can be used to control strain effects and tune the activity, stability, and reactivity of these materials.