EFFECT OF ACOUSTIC EXCITATION ON THE RATE OF CO OXIDATION OVER PT(110)

A unique UHV-compatible excitation system combined with an advanced ul tra-high amplitude and frequency resolution acoustic spectrometer has been designed and constructed to permit accurate studies of the fundam ental mechanism by which acoustic excitation may influence heterogeneo us catalytic reactions. Here, the first results are presented, which d emonstrate a remarkable sixfold increase in the rate of carbon monoxid e oxidation when a Pt{110} thin single crystal is excited with low-fre quency, low-energy surface acoustic waves (Rayleigh waves). In additio n, chemical oscillations in the CO2 production rate are found to be in itiated and influenced by acoustic excitation of the system. It is pro posed that the acoustic excitation results in an enhancement of the ca rbon monoxide desorption, which in turn affects the activity of the pl atinum catalyst if the reaction is in the transition between a low- an d high-rate branch. (C) 1998 Elsevier Science B.V. All rights reserved .