AVS 50th International Symposium
    Surface Science Friday Sessions
       Session SS1-FrM

Paper SS1-FrM8
A Model Catalyst with Selectivity Controllable Functions: the Effects of Thickness Extensional Resonance Oscillation on the Catalytic Activities for Ethanol Decomposition of Thin AgAu Film Alloy Deposited on a Ferroelectric z-cut LiNbO@sub 3@ Crystal

Friday, November 7, 2003, 10:40 am, Room 327

Session: Catalysis IV: Reactivity of Complex Systems
Presenter: N. Saito, Nagaoka University of Technology, Japan
Authors: N. Saito, Nagaoka University of Technology, Japan
Y. Sato, Nagaoka University of Technology, Japan
Y. Yukawa, Nagaoka University of Technology, Japan
H. Nishiyama, Nagaoka University of Technology, Japan
Y. Inoue, Nagaoka University of Technology, Japan
Correspondent: Click to Email
In an attempt to design a heterogeneous catalyst that has artificially controllable functions for catalytic reactions, we have employed the resonance oscillation (RO) of acoustic wave generated on a poled ferroelectric crystal and demonstrated that the thickness extension mode resonance oscillation (TERO) has the ability to change the reaction selectivity over thin metal catalysts deposited on a z-cut LiNbO@sub 3@ crystal.@footnote 1@ The effects of TERO are suggested to have strong influences on the electronic states of metal catalysts, and it is particular interesting to apply the TERO for alloy catalysts consisting of more than one component surface metal atom with different electronic structures. In the present study, we investigated the TERO effects on catalytic ethanol decomposition on AgAu alloy catalysts. The AgAu alloy catalysts were prepared by consecutive deposition of Au and Ag, followed by heat treatment at high temperature enough to allow the metal phases to diffuse and to uniformly mix each other. In catalytic run on a Ag catalyst, the TERO increased ethylene activity without changes in acetaldehyde, indicating that the TERO activate only ethylene production on a single Ag metal surface. On the other hand, the TERO with AgAu catalysts increased the activity for acetaldehyde significantly. The activity enhancement increased with increasing Au content, passed through a maximum at 80% and decreased sharply. Laser Doppler measurement showed that lattice displacement generated by the TERO became the smallest at the same Au content (80%) as that where the TERO effect on the activity for acetaldehyde was the highest. This indicates that the nature and strength of Ag-Au bonds plays in an important role in the TERO-induced activity enhancement. Similar results were also observed for AgCu alloys. The mechanism of different TERO effects between Ag and Ag-based metal alloys is discussed. @FootnoteText@ @footnote 1@ N.Saito and Y.Inoue, J.Phys.Chem.B, 107/9, 2040(2003).