Surface morphological changes induced in catalysts by acoustic waves

An interdigital transducer device equipped with a metal catalyst sample that can be used to enhance catalytic activity by acoustic excitation is investigated. It was found that the propagation of 20 MHz surface acoustic waves of the Rayleigh type on Pt thin film single crystals causes drastic changes in surface morphology. The process of film breaking is observed and it is concluded that a phase shift in the acoustic wave induced by folds and cavities in the sample is responsible for the appearance of cracks. The influence of the change in morphology on catalytic activity and the acoustically induced rate enhancement effect is studied, and it is concluded that these changes are not a significant factor in the observed enhancement. q1999 Elsevier Science B.V. All rights reserved.