A 100-nm thick Ag film was deposited on a positively polarized z-cut LiNbO 3 ferroelectric substrate, and the effects of thickness extension mode resonance oscillation (TERO) of bulk acoustic waves generated by rf electric power on the catalytic properties were studied. In ethanol decomposition, the TERO caused a remarkable increase in ethylene production without changes in acetaldehyde production, and the activation energy for ethylene production decreased considerably. The activity for ethylene production increased in a nonlinear manner with increasing rf power, and its selectivity resulted in a marked enhancement. A laser Doppler method demonstrated that the TERO produced randomly distributed standing waves with large lattice displacement vertical to the surface. In photoelectron emission spectra, the TERO caused a positive shift of the threshold energy in photoelectron emission from the Ag surface, which was indicative of an increase in a work function-related parameter in the presence of TERO. The vertical dynamic lattice displacement is proposed to be responsible for positive work function shifts. Correlation existed between activity enhancement and the work function shift, which indicated that activity enhancements with TERO are associated with increases in the work function. A mechanism of TERO effects on selectivity changes is discussed.

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The effects of thickness extension mode resonance oscillation (TERO) of bulk acoustic waves on ethanol decomposition over a 100 nm Ag film deposited on a negatively polarized z-cut LiNbO 3 crystal ((-)Ag) were studied, and the results were compared with those obtained previously for Ag deposited on a positively polarized z-cut LiNbO 3 crystal ((+)Ag). In ethylene and acetaldehyde production, the TERO for (-)Ag increased the selective for ethylene production, but the TERO effects on activity and selectivity enhancement were smaller compared to those for (+)Ag. Laser Doppler measurements showed that lattice displacements caused by the TERO were similar between (-)Ag and (+)Ag. In photoelectron emission spectra of (-)Ag, the TERO caused the positive shifts of the threshold energy for electron emission associated with the work function of the Ag surface. The work function increases were considerably smaller for (-)Ag than for (+)Ag, which is considered to be responsible for differences in the catalyst activation between (-)Ag and (+)Ag. A mechanism of different TERO effects between (-)Ag and (+)Ag is discussed.

The effects of thickness extension mode resonance oscillation (TERO) of acoustic waves on the catalytic properties of a 100 nm thick Pd film deposited a positively polarized ferroelectric z-cut LiNbO 3 single crystal were studied. For ethylene and acetaldehyde production in ethanol decomposition, the TERO accelerated ethylene production only and enhanced the selectivity for ethylene production from 40% to 96%. Randomly distributed standing waves due to large lattice displacement vertical to the surface were generated with TERO on. The photoelectron emission spectra showed that the TERO caused a positive shift of the threshold energy of photoelectron emission from a Pd surface, indicating an increase in the work function of the surface. The TERO effects on a Pd catalyst were compared with those previously observed for a Ag catalyst.

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