title: Carbon-supported Pt^Ag nanostructures as cathode catalysts for oxygen reduction reaction.
abstract: Pt(m)^Ag nanostructures (m being the atomic Pt/Ag ratio, m = 0.1-0.6) were prepared by reflux citrate reduction of PtCl(6)(2-) ions in aqueous solution containing colloidal Ag (6.3 ± 3.9 nm). A distinct alloying of Pt with Ag was detected due to an involvement of the galvanic replacement reaction between PtCl(6)(2-) and metallic Ag colloids. The nanostructure transformed from a structure with an Ag-core and an alloyed PtAg-shell to a hollow PtAg alloy structure with the increase in m. Compared to a commercial E-TEK Pt/C catalyst, the catalytic performance of Pt in the Pt(m)^Ag/C samples for the cathode oxygen reduction reaction (ORR) strongly correlated with the electronic structure of Pt, as a consequence of varied Pt dispersion and Pt-Ag interaction. With either H(2)SO(4) or KOH as an electrolyte, Pt in the Pt(m)^Ag nanostructures with a relatively high m (≥0.4) showed significantly enhanced intrinsic activity whereas Pt in those catalysts with low m (≤0.2) appeared less active than the Pt/C catalyst. These data are used to discuss the role of electronic structure and geometric effects of Pt toward ORR.
authors.affiliation: Innovative Catalysis Program, Key Lab of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Feng
authors.forename: Gui-Rong
authors.initials: GR
authors.lastname: Zhang
authors.forename: Jun-Hong
authors.initials: JH
authors.lastname: Ma
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Bo-Qing
authors.initials: BQ
authors.lastname: Xu