Acoustic wave effects on catalysis: design of surfaces with arti®cially controllable functions for chemical reactions

The effects of surface acoustic wave (SAW) and resonance oscillation (RO) of bulk acoustic waves on the catalysis of metals were studied in an attempt to design a catalyst surface with arti®cially controllable functions for chemical reactions. In ethanol decomposition on a thin Cu ®lm catalyst deposited on the propagation path of a shear horizontal leaky SAW, the SAWon increased the activity for ethylene production remarkably but a little for acetaldehyde production. A poled ferroelectric zcut LiNbO3 with a thickness extensional mode RO (TERO) and a x-cut LiNbO3 with a thickness shear mode RO (TSRO) were employed as a substrate, on which a thin Ag ®lm catalyst was deposited. For ethanol decomposition, TERO increased ethylene production activity and the selectivity for ethylene production from 79 to 96%, whereas TSRO caused little activity enhancement for both ethylene and acetaldehyde production. The combination with the results of laser Doppler measurements showed that the activity enhancement and selectivity changes with SAW and RO of the acoustic waves are associated with dynamic large lattice displacement vertical to the surface. # 2001 Published by Elsevier Science B.V.