Influence of acoustic wave excitation on CO oxidation over a Pt{110} single crystal

Abstract

A unique ultra-high vacuum (UHV) compatible excitation system combined with an advanced ultra-high amplitude and frequency resolution acoustic spectrometer has been designed and constructed to permit accurate studies of the fundamental mechanism by which acoustic excitation influences heterogeneous catalytic reactions. A clean Pt{110} thin film single-crystal catalyst was excited with low-energy acoustic waves (Rayleigh waves) under high vacuum and UHV conditions to increase the reaction rate for carbon monoxide oxidation. A remarkable six-fold increase in the chemical activity was observed. By using a new, very accurate method to monitor the sample temperature using high-resolution acoustic wave resonance spectroscopy (HRAWRS), a non-thermal acoustic-wave-induced enhancement of the reaction rate is clearly demonstrated. The pressure and temperature dependences of the enhancement provide some insight into the mechanism by which acoustic waves enhance catalytic reactions on solid surfaces.

References

1. For a review see: M. Gruyters, T. Mitrelias and D. A. King, Appl. Phys. A, 1995, 61, 243.
2. T. J. Mason and J. P. Lorimer, Practical Sonochemistry, Ellis Horwood, New York, 1991.
3. B. P. Barber, R. Hiller, K. Arisaka, H. Fetterman and S. J. Putterman, J. Acoust. Soc. Am., 1992, 91, 3061.
4. R. J. Zanetti, Chem. Eng., 1992, 99, 37.
5. K. S. Suslick, Science, 1990, 247, 1439.
6. N. A. Maksimenko and M. A. Margulis, Russ. J. Phys. Chem., 1992, 66, 396.
7. Y. Inoue, Y. Matsukawa and K. Sato, J. Chem. Phys., 1992, 96, 2222.
8. Y. Inoue and Y. Matsukawa, Chem. Phys. Lett., 1992, 198, 246.
9. Y. Inoue, J. Chem. Soc., Faraday Trans., 1994, 90, 815.
10. Y. Inoue, Y. Watanabe and T. Noguchi, J. Phys. Chem., 1995, 99, 9898.
11. Y. Inoue, M. Matsukawa and H. Kawaguchi, J. Chem. Soc., Faraday Trans., 1992, 88, 2923.
12. T. Mitrelias, S. Kelling, R. I. Kvon, V. P. Ostanin and D. A. King, Surf. Sci., submitted.
13. S. Kelling, T. Mitrelias, Y. Matsumoto, V. P. Ostanin and D. A. King, J. Chem. Phys., in press.
14. T. Mitrelias, S. Kelling, M. Gruyters and D. A. King, Appl. Phys. Lett., 1996, 69, 3677.
15. T. Mitrelias, V. P. Ostanin, M. Gruyters and D. A. King, Appl. Surf. Sci., 1996, 101, 105.
16. J. L. Falconer and R. J. Madix, Surf. Sci., 1985, 160, 393.
17. Y. Y. Yeo, C. E. Wartnaby and D. A. King, Science, 1995, 268, 1731.
18. V. N. Brezhnev, A. I. Boronin, V. P. Ostanin, V. S. Tupikov and A. N. Belyaev, Chem. Phys. Lett., 1992, 191, 379.
19. Y. Inoue, personal communication.
20. S. Ladas, R. Imbihl and G. Ertl, Surf Sci., 1988, 197, 153.
21. M. Hirano and K. Shinjo, Phys. Rev. B, 1990, 41, 11837.
22. K. Shinjo and M. Hirano, Surf. Sci., 1993, 283, 473.
23. M. Hirano, K. Shinjo, R. Kaneko and Y. Murata, Phys. Rev. Lett., 1997, 78, 1448.
24. H. H. Rotermund, Surf. Sci., 1993, 283, 87.