Article

Tuning reaction rates by lateral strain in a palladium monolayer.

Abteilung Elektrochemie, Universität Ulm, 89069 Ulm, Germany.
Angewandte Chemie International Edition (Impact Factor: 11.34). 04/2005; 44(14):2080-4. DOI: 10.1002/anie.200462127
Source: PubMed
0 Followers
 · 
80 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In order to extend the dealloying systems and their electrocatalytic applications, in this work, electrocatalysis of ethanol in alkaline media on dealloyed Pd-Ni-P film is selected as a case study. Pd-Ni-P film is prepared via electro-deposition on Au substrate, and the dealloying process is carried out by repetitive potential cycling in acidic media to leach out most Ni and P components. The surface structural and electronic properties of the as-deposited film and the dealloyed film are characterized and compared using field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy. Surface roughening, Pd-segregation and electronic property variation upon dealloying are confirmed. Cyclic voltammetry and chronoamperometry on the two films in ethanol-containing alkaline media are used to assess their electrocatalytic performances, demonstrating significantly enhanced and durable ethanol oxidation on the dealloyed film. More importantly, in situ attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) is initially applied to explore the interfacial molecular information in the electrocatalysis on these two films to provide molecular insight into the enhanced electrocatalytic activity on the dealloyed film, revealing that the enhanced electrocatalysis correlates well with enhanced formation of both COad and acetate.
    Electrochimica Acta 04/2015; 162:100-107. DOI:10.1016/j.electacta.2014.11.182 · 4.09 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have rationally synthesized and optimized catalytic nanoparticles consisting of a gold core, covered by a palladium shell, onto which platinum clusters are deposited (Au@Pd@Pt NPs). The amount of Pt and Pd used is extremely small, yet they show unusually high activity for electrooxidation of formic acid. The optimized structure has only 2 atomic layers of Pd and a half-monolayer equivalent of Pt (q Pt z 0.5) but a further increase in the loading of Pd or Pt will actually reduce catalytic activity, inferring that a synergistic effect exists between the three different nanostructure components (sphere, shell and islands). A combined electrochemical, surface-enhanced Raman scattering (SERS) and density functional theory (DFT) study of formic acid and CO oxidation reveals that our core–shell–cluster trimetallic nanostructure has some unique electronic and morphological properties, and that it could be the first in a new family of nanocatalysts possessing unusually high chemical reactivity. Our results are immediately applicable to the design of catalysts for direct formic acid fuel cells (DFAFCs).
    Chemical Science 02/2011; 2(3). DOI:10.1039/C0SC00489H · 8.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Diffraction of H2 from surfaces is considered to be a useful tool to characterize molecule/surface interactions and surface topology. In this work, we have studied diffraction of H2 from a strained pseudomorphic monolayer of Cu deposited on Ru(0001), both experimentally and theoretically. Our experimental measurements show a remarkable diffraction probability, both in-plane and out-of-plane. In particular, we observe for the first time third-order diffraction peaks. These striking experimental results have been analyzed by performing theoretical simulations, using both quantum and quasi-classical dynamics methods. Taking into account the relationship between diffraction (quantum phenomenon) and reflection (classical observable), we have performed a classical analysis of a meaningful set of classical trajectories. This analysis reveals that for H2/Cu/Ru(0001) diffracted molecules practically explore the entire surface unit cell and are able to get close to the surface, thus favoring high-order diffraction.
    The Journal of Physical Chemistry C 06/2012; 116(25):13671-13678. DOI:10.1021/jp303390x · 4.84 Impact Factor