IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Electrochemistry and Fluid-Solid Interfaces Monday Sessions
       Session EC-MoA

Paper EC-MoA5
Electrochemical Epitaxial Growth of Palladium Thin Layers on Au(111) and Au(100) Electrodes and Their Electrocatalytic Properties

Monday, October 29, 2001, 3:20 pm, Room 111

Session: Electrochemical Control of Surface Structure: Growth and Dissolution
Presenter: K. Uosaki, Hokkaido University, Japan
Authors: K. Uosaki, Hokkaido University, Japan
S. Ye, Hokkaido University, Japan
H. Naohara, Hokkaido University, Japan
T. Kondo, Hokkaido University, Japan
K. Tamura, Hokkaido University, Japan
M. Takahasi, Japan Atomic Energy Research Institute, Japan
J. Mizuki, Japan Atomic Energy Research Institute, Japan
Correspondent: Click to Email
It is well known that the physical and chemical properties of a metal ultrathin layer on a foreign substrate are different from those of the bulk metal.In the present study, the electrochemical epitaxial growth processes of Pd on Au(111) and Au(100) electrodes were investigated by using in situ scanning tunneling microscopy (STM)@footnote 1,2@ and surface X-ray scattering (SXS).@footnote 3@ The effect of the thickness on the electrocatalytic activity for the anodic oxidation of formaldehyde at the Pd thin layers on the Au(111) and Au(100) substrates was also investigated.@footnote 4@ Electrochemical deposition of Pd was carried out in HClO@sub 4@ solution containing PdCl@sub 4@@super 2-@ complex. Electrochemical oxidation of formaldehyde on the deposited Pd layers was studied in HClO@sub 4@ solution containing formaldehyde. In situ STM measurements showed that palladium was grown epitaxially on both the Au(111)@footnote 1@ and Au(100) substrates.@footnote 2@ SXS measurements proved that the lattice parameters of the first Pd layer on Au(111) and Au(100) substrates were different from those of the bulk Pd crystal but same as those of the gold substrates.@footnote 3@ The electrocatalytic activity for oxidation of formaldehyde depends strongly on the structure and thickness of Pd thin layers. The peak current for formaldehyde oxidation at the Pd/Au(100) surfaces was much higher than that at the Pd/Au(111) surfaces. The peak potentials of anodic peaks corresponding to formaldehyde oxidation were shifted to negative direction as the thickness increased, reflecting the thickness dependent potential shift for oxide formation/reduction on the ultra thin layers of Pd. @FootnoteText@@footnote 1@H. Naohara, S. Ye, K. Uosaki, J. Phys. Chem. B, 102, 4366 (1998). @footnote 2@H. Naohara, S. Ye, K. Uosaki, J. Electroanal. Chem., 473, 2 (1999). @footnote 3@M. Takahashi, Y. Hayashi, J. Mizuki, K. Tamura, T. Kondo, H. Naohara, K. Uosaki, Surf. Sci., Surf. Sci., 461, 213 (2000). @footnote 4@H. Naohara, S. Ye, K. Uosaki, J. Electroanal. Chem., 500, 435 (2000).