Russian Journal of Electrochemistry

, Volume 37, Issue 1, pp 102–106 | Cite as

Isotope Separation Factor and Kinetic Isotopic Effect of the Hydrogen Evolution Reaction

  • L. I. Krishtalik
Article

Abstract

The hydrogen isotope separation factor decreases with increasing overvoltage on mercury-like electrodes in acid solutions. This dependence qualitatively differs from that for the ratio between hydrogen evolution rates in light and heavy water, which increases with polarization. The reason for the difference is that the isotope separation factor depends on the kinetic isotopic effect (KIE) in two reaction stages: discharge and electrochemical desorption. Experimental data show that a decrease in KIE with potential in the latter stage outweighs the increase in KIE in the former. The KIE decreases in the desorption reaction because this process is activationless; therefore, there is no potential dependence of the relative contribution made by vibrationally excited states of the product in this case, i.e. no dependence that is responsible for the increase in KIE at the discharge stage. The same factor has no effect on KIE for a barrierless discharge, which also decreases with increasing overvoltage. Thus, all experimentally observed dependences of KIE on potential are explained in the framework of a unified approach.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

REFERENCES

  1. 1.
    Bunakova, L.V., Kriksunov, L.B., and Tsionskii, V.M., Elektrokhimiya, 1992, vol. 28, p. 275.Google Scholar
  2. 2.
    Bockris, J.O'M. and Srinivasan, S., J. Electrochem. Soc., 1964, vol. 111, p. 844.Google Scholar
  3. 3.
    Krishtalik, L.I., Elektrokhimiya, 1970, vol. 6, p. 1456.Google Scholar
  4. 4.
    Albery, W.J., in Progress in Reaction Kinetics, Porter, G., Ed., 1967, vol. 4, p. 353.Google Scholar
  5. 5.
    Spravochnik khimika (Handbook of Chemist), Nikol'skii, B.P., Ed., Moscow: Khimiya, 1966, vol. 1.Google Scholar
  6. 6.
    Post, B. and Hiskey, C.F., J. Am. Chem. Soc., 1950, vol. 72, p. 4203.Google Scholar
  7. 7.
    Post, B. and Hiskey, C.F., J. Am. Chem. Soc., 1951, vol. 73, p. 161.Google Scholar
  8. 8.
    Rome, M. and Hiskey, C.F., J. Am. Chem. Soc., 1954, vol. 76, p. 5207.Google Scholar
  9. 9.
    Drucker, C., Trans. Faraday Soc., 1937, vol. 33, p. 660.Google Scholar
  10. 10.
    Gold, V. and Lowe, B.M., Trans. Faraday Soc., 1969, vol. 65, p. 3037.Google Scholar
  11. 11.
    CRC Handbook of Chemistry and Physics, Boca Raton: CRC, 1996.Google Scholar
  12. 12.
    Bell, R., The Proton in Chemistry, London: Chapman and Hall, 1973.Google Scholar
  13. 13.
    Melander, L. and Saunders, W., Reaction Rates of Isotopic Molecules, New York: Wiley, 1980.Google Scholar
  14. 14.
    Krishtalik, L.I., Elektrokhimiya, 1979, vol. 15, p. 435.Google Scholar
  15. 15.
    Krishtalik, L.I., Mertz, E.L., and Topolev, V.V., in Electron and Ion Transfer in Condensed Media, Kornyshev, A.A., Tosi, M., and Ulstrup, J., Eds., Singapore: World Scientific, 1997, p. 277.Google Scholar
  16. 16.
    Tsionskii, V.M. and Krishtalik, L.I., Elektrokhimiya, 1969, vol. 5, p. 1184.Google Scholar
  17. 17.
    Krishtalik, L.I., Biochim. Biophys. Acta, 2000, vol. 1458, p. 6.Google Scholar
  18. 18.
    Krishtalik, L.I., Bunakova, L.V., and Shumskaya, S.E., Elektrokhimiya, 1998, vol. 34, p. 1354.Google Scholar
  19. 19.
    Krishtalik, L.I., Elektrokhimiya, 1991, vol. 27, p. 303.Google Scholar
  20. 20.
    Krishtalik, L.I., Elektrodnye reaktsii: Mekhanizm elementarnogo akta (Electrode Reactions: The Mechanism of an Elementary Act), Moscow: Nauka, 1979.Google Scholar
  21. 21.
    Tsionskii, V.M., Cand. Sci. (Chem.) Dissertation, Moscow: Frumkin Inst. of Electrochem., 1969.Google Scholar
  22. 22.
    Potapova, E.N., Krishtalik, L.I., and Bagotskaya, I.A., Elektrokhimiya, 1974, vol. 10, p. 49.Google Scholar
  23. 23.
    Potapova, E.N., Krishtalik, L.I., and Bagotskaya, I.A., Elektrokhimiya, 1974, vol. 10, p. 53.Google Scholar
  24. 24.
    Benderskii, V.A. and Grebenshchikov, S.Yu., J. Electroanal. Chem., 1994, vol. 375, p. 29.Google Scholar

Copyright information

© MAIK “Nauka/Interperiodica” 2001

Authors and Affiliations

  • L. I. Krishtalik
    • 1
  1. 1.Frumkin Institute of ElectrochemistryRussian Academy of SciencesMoscowRussia

Personalised recommendations