title: Tuning oxygen reduction reaction activity via controllable dealloying: a model study of ordered Cu3Pt/C intermetallic nanocatalysts.
abstract: A promising electrocatalyst prototype of low Pt mole fraction, intermetallic nanoparticles of Cu(3)Pt, has been prepared using a simple impregnation-reduction method, followed by a post heat-treatment. Two dealloying methods (electrochemical and chemical) were implemented to control the atomic-level morphology and improve performance for the oxygen reduction reaction (ORR). The morphology and elemental composition of the dealloyed nanoparticles were characterized at angstrom resolution using an aberration-corrected scanning transmission electron microscope equipped with an electron energy loss spectrometer. We found that the electrochemical dealloying method led to the formation of a thin Pt skin of ca. 1 nm in thickness with an ordered Cu(3)Pt core structure, while chemical leaching gave rise to a "spongy" structure with no ordered structure being preserved. A three-dimensional tomographic reconstruction indicated that numerous voids were formed in the chemically dealloyed nanoparticles. Both dealloying methods yielded enhanced specific and mass activities toward the ORR and higher stability relative to Pt/C. The spongy nanoparticles exhibited better mass activity with a slightly lower specific activity than the electrochemically dealloyed nanoparticles after 50 potential cycles. In both cases, the mass activity was still enhanced after 5000 potential cycles.
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Deli
authors.initials: D
authors.lastname: Wang
authors.forename: Yingchao
authors.initials: Y
authors.lastname: Yu
authors.forename: Huolin L
authors.initials: HL
authors.lastname: Xin
authors.forename: Robert
authors.initials: R
authors.lastname: Hovden
authors.forename: Peter
authors.initials: P
authors.lastname: Ercius
authors.forename: Julia A
authors.initials: JA
authors.lastname: Mundy
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Jonah H
authors.initials: JH
authors.lastname: Richard
authors.forename: David A
authors.initials: DA
authors.lastname: Muller
authors.forename: Francis J
authors.initials: FJ
authors.lastname: DiSalvo
authors.forename: Héctor D
authors.initials: HD
authors.lastname: Abruña