Artificial control of heterogeneous catalysis by dynamic lattice displacement of surface acoustic waves and resonance oscillations

摘要

The effects of surface acoustic waves (SAWs) andresonance oscillations (ROs) on the activity and selectivity ofheterogeneous catalysts were reviewed. In ethanol oxidation overa Pd thin film deposited on the SAW propagation path, the SAWeffects were greater for thicker Pd films and for oxidized surfacesthan for metallic ones. Lattice displacement measurements andSAW propagation loss showed that the SAW effects of theoxidized catalyst surface are attributed to the interactionsbetween electrons in the oxide layers and SAW. In RO of a poledferroelectric Sr-doped lead zirconium titanate, the effects of athickness extensional mode on ethanol oxidation over a Agcatalyst were associated with changes in surface potential andwork functions of the Ag surface with RO. RO using aferroelectric LiNbO3 single crystal caused a remarkably higheractivity enhancement for ethanol oxidation on Pd and a selectivitychange leading to higher ethylene production in the dehydrationand dehydrogenation of ethanol on W03. The SAWs and ROs areconcluded to be useful for the design of a heterogeneous catalystwhich has artificially controllable functions for chemical reactions.