title: Surface structures and electrochemical activities of Pt overlayers on Ir nanoparticles.
abstract: Pt overlayers were deposited on carbon-supported Ir nanoparticles with various coverages. Structural and electrochemical characterizations were performed using transmission electron microscopy (TEM), X-ray diffraction, high-resolution powder diffraction (HRPD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES), cyclic voltammetry (CV), CO stripping voltammetry, and N2O reduction. The surface of Ir nanoparticles was covered with Pt overlayers with thickness varying from the submonolayer scale to more than two monolayers. Surface analyses such as CV and CO stripping voltammetry indicated that the Pt overlayers were uniformly deposited on the Ir nanoparticles, and the resultant Pt overlayers exhibited gradual changes in surface characteristics toward the Pt surface as the surface coverage increased. The distinct CO stripping characteristics and the enhanced Pt utilization affected electrocatalytic activities for methanol oxidation. The electrochemical stability of the Pt overlayer was compared with a commercial carbon-supported Pt catalyst by conducting a potential cycling experiment.
authors.affiliation: World Class University Program of Chemical Convergence for Energy & Environment, School of Chemical and Biological Engineering, Seoul National University (SNU) , Seoul 151-744, South Korea.
authors.forename: Kug-Seung
authors.initials: KS
authors.lastname: Lee
authors.forename: Sung Jong
authors.initials: SJ
authors.lastname: Yoo
authors.forename: Docheon
authors.initials: D
authors.lastname: Ahn
authors.forename: Tae-Yeol
authors.initials: TY
authors.lastname: Jeon
authors.forename: Kwang Hyun
authors.initials: KH
authors.lastname: Choi
authors.forename: In-Su
authors.initials: IS
authors.lastname: Park
authors.forename: Yung-Eun
authors.initials: YE
authors.lastname: Sung