title: Tuning the activity of Pt alloy electrocatalysts by means of the lanthanide contraction.
abstract: 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.
authors.affiliation: Center for Individual Nanoparticle Functionality (CINF), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark. Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA. ibchork@fysik.dtu.dk ifan@fysik.dtu.dk maria.escudero@fysik.dtu.dk.
authors.forename: María
authors.initials: M
authors.lastname: Escudero-Escribano
authors.affiliation: Center for Individual Nanoparticle Functionality (CINF), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark.
authors.forename: Paolo
authors.initials: P
authors.lastname: Malacrida
authors.affiliation: Center for Atomic-Scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark. Nano-Science Center, Department of Chemistry, University of Copenhagen, 2100 Copenhagen, Denmark.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Hansen
authors.affiliation: Center for Individual Nanoparticle Functionality (CINF), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark. Center for Atomic-Scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark.
authors.forename: Ulrik G
authors.initials: UG
authors.lastname: Vej-Hansen
authors.affiliation: Center for Individual Nanoparticle Functionality (CINF), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark.
authors.forename: Amado
authors.initials: A
authors.lastname: Velázquez-Palenzuela
authors.affiliation: Center for Atomic-Scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark. Department of Energy Conversion and Storage, Technical University of Denmark, 4000 Roskilde, Denmark.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Tripkovic
authors.affiliation: Center for Individual Nanoparticle Functionality (CINF), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark. Center for Atomic-Scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Schiøtz
authors.affiliation: Center for Atomic-Scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark. Nano-Science Center, Department of Chemistry, University of Copenhagen, 2100 Copenhagen, Denmark.
authors.forename: Jan
authors.initials: J
authors.lastname: Rossmeisl
authors.affiliation: Center for Individual Nanoparticle Functionality (CINF), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark. Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. ibchork@fysik.dtu.dk ifan@fysik.dtu.dk maria.escudero@fysik.dtu.dk.
authors.forename: Ifan E L
authors.initials: IE
authors.lastname: Stephens
authors.affiliation: Center for Individual Nanoparticle Functionality (CINF), Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark. ibchork@fysik.dtu.dk ifan@fysik.dtu.dk maria.escudero@fysik.dtu.dk.
authors.forename: Ib
authors.initials: I
authors.lastname: Chorkendorff