Artificial control of reaction selectivity on Ag metal surface by dynamic lattice displacement of acoustic waves

The effects of different vibration modes of resonance oscillation (RO) on the reaction selectivity of ethanol decomposition over an Ag catalyst were studied. A z-cut and an x-cut LiNbO3 ferroelectric single crystal were used as a substrate, onto which a 100 nm Ag thin film catalyst was deposited. A z-cut and an x-cut LiNbO3 ferroelectric single crystal were shown to provide a thickness extensional (TE) and a thickness shear (TS) mode vibration, respectively. The TE mode RO increased ethylene production without significant enhancement of acetaldehyde production, whereas the TS mode RO caused little increases for both ethylene and acetaldehyde production. In laser Doppler measurements of lattice displacement vertical to the surface, irregular standing wave patterns were induced by RO, and the lattice displacement was significantly large for the TE mode and very small for the TS mode RO.