title: Electrochemical synthesis of mesoporous Pt-Au binary alloys with tunable compositions for enhancement of electrochemical performance.
abstract: Mesoporous Pt-Au binary alloys were electrochemically synthesized from lyotropic liquid crystals (LLCs) containing corresponding metal species. Two-dimensional exagonally ordered LLC templates were prepared on conductive substrates from diluted surfactant solutions including water, a nonionic surfactant, ethanol, and metal species by drop-coating. Electrochemical synthesis using such LLC templates enabled the preparation of ordered mesoporous Pt-Au binary alloys without phase segregation. The framework composition in the mesoporous Pt-Au alloy was controlled simply by changing the compositional ratios in the precursor solution. Mesoporous Pt-Au alloys with low Au content exhibited well-ordered 2D hexagonal mesostructures, reflecting those of the original templates. With increasing Au content, however, the mesostructural order gradually decreased, thereby reducing the electrochemically active surface area. Wide-angle X-ray diffraction profiles, X-ray photoelectron spectra, and elemental mapping showed that both Pt and Au were atomically distributed in the frameworks. The electrochemical stability of mesoporous Pt-Au alloys toward methanol oxidation was highly improved relative to that of nonporous Pt and mesoporous Pt films, suggesting that mesoporous Pt-Au alloy films are potentially applicable as electrocatalysts for direct methanol fuel cells. Also, mesoporous Pt-Au alloy electrodes showed a highly sensitive amperometric response for glucose molecules, which will be useful in next-generation enzyme-free glucose sensors.
authors.affiliation: World Premier International (WPI) Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan. Yamauchi.Yusuke@nims.go.jp
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yamauchi
authors.forename: Akihisa
authors.initials: A
authors.lastname: Tonegawa
authors.forename: Masaki
authors.initials: M
authors.lastname: Komatsu
authors.forename: Hongjing
authors.initials: H
authors.lastname: Wang
authors.forename: Liang
authors.initials: L
authors.lastname: Wang
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nemoto
authors.forename: Norihiro
authors.initials: N
authors.lastname: Suzuki
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kuroda