title: Platinum monolayer on nonnoble metal-noble metal core-shell nanoparticle electrocatalysts for O2 reduction.
abstract: We synthesized a new class of O2 electrocatalysts with a high activity and very low noble metal content. They consist of Pt monolayers deposited on the surfaces of carbon-supported nonnoble metal-noble metal core-shell nanoparticles. These core-shell nanoparticles were formed by segregating the atoms of the noble metal on to the nanoparticles' surfaces at elevated temperatures. A Pt monolayer was deposited by galvanic displacement of a Cu monolayer deposited at underpotentials. The mass activity of all the three Pt monolayer electrocatalysts investigated, viz., Pt/Au/Ni, Pt/Pd/Co, and Pt/Pt/Co, is more than order of magnitude higher than that of a state-of-the-art commercial Pt/C electrocatalyst. Geometric effects in the Pt monolayer and the effects of PtOH coverage, revealed by electrochemical data, X-ray diffraction, and X-ray absorption spectroscopy data, appear to be the source of the enhanced catalytic activity. Our results demonstrated that high-activity electrocatalysts can be devised that contain only a fractional amount of Pt and a very small amount of another noble metal.
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: F H B
authors.initials: FH
authors.lastname: Lima
authors.forename: M H
authors.initials: MH
authors.lastname: Shao
authors.forename: K
authors.initials: K
authors.lastname: Sasaki
authors.forename: J X
authors.initials: JX
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Hanson
authors.forename: R R
authors.initials: RR
authors.lastname: Adzic