title: Enhanced activity for oxygen reduction reaction on "Pt3Co" nanoparticles: direct evidence of percolated and sandwich-segregation structures.
abstract: Atomically resolved structures and compositions of Pt alloy nanoparticles were obtained using aberration-corrected high-angle dark field imaging, which was correlated to specific ORR activity based on a Pt surface area. The enhanced specific ORR activity (approximately 2 times relative to Pt) of acid-treated "Pt3Co" nanoparticles can be related to composition variations at the atomic scale and the formation of percolated Pt-rich and Pt-poor regions within individual particles. Upon annealing, we show direct evidence of surface Pt sandwich-segregation structures, which correspond to a specific ORR activity approximately 4 times relative to Pt.
authors.affiliation: Electrochemical Energy Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Shuo
authors.initials: S
authors.lastname: Chen
authors.forename: Paulo J
authors.initials: PJ
authors.lastname: Ferreira
authors.forename: Wenchao
authors.initials: W
authors.lastname: Sheng
authors.forename: Naoaki
authors.initials: N
authors.lastname: Yabuuchi
authors.forename: Lawrence F
authors.initials: LF
authors.lastname: Allard
authors.forename: Yang
authors.initials: Y
authors.lastname: Shao-Horn