Artificial control of reaction selectivity for ethanol decomposition on Ag catalyst by resonance oscillation: effects of resonance frequency

摘要

Thickness extension mode resonance oscillation (TERO) generated on ferroelectric z-cut LiNbO_3 single crystals by rf power was applied to a thin Ag film catalyst deposited on the crystals. The TERO of three different resonance frequencies at 3.5, 10.8 and 17.9 MHz showed not only remarkable increases in ethylene production without a significant changes in acetaldehyde production but also different enhancement of ethylene production. In a high power regime (>1 W), activation by TERO for ethylene production increased in the order 3.5>10.8>17.9 MHz. In a low power regime (<1 W), the activation order for ethylene production was 10.8>3.5>17.9 MHz. In laser Doppler measurements, with increasing resonance frequency, lattice displacement due to standing waves decreased, whereas standing wave density increased. Photoelectron emission measurements showed that TERO increased a work function-relating parameter of the Ag catalyst surface. On the basis of these results, TERO effects with three different resonance frequencies on catalyst activation are discussed.