Abstract
Fluorine-evolving carbon anodes exhibit unusually high overvoltages characterized also by remarkably large Tafel slopes having values 0.4–0.8 V per decade of current density change. Also, at high current densities, a so-called ‘anode effect’ associated with a type of passivation sets in. Experiments are described which aim to distinguish high polarization arising from an intrinsically large Tafel slope, generated by a non-ohmic charge transfer barrier layer effect due to ‘CF’ film formation, from effects due to difficulties of F2 bubble detechment and F2 gas film formation at the ‘CF’ film. Steady state polarization measurements have been made at a rotating carbon cone electrode from which F2 bubbles, which otherwise remain attached to the electrode and block access to the electrolyte, can be spun away. At the rotated electrode, at low and intermediate current densities, linear Tafel behaviour is still observed but with high slopes associated with the barrier layer film effect. At higher current densities an ‘anode effect’, associated with the F2 gas film, is developed, leading to a type of passivation of the electrode. The two sources of unusually high polarization in the F2 evolution reaction at carbon are not independent as it is also the formation of the ‘CF’ film that causes difficulties in gas bubble detachment owing to the lyophobic properties of the fluorinated C/F2/KF·2HF interface. Polishing effects confirm this conclusion.
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M. Chemla, D. Devilliers and F. Lantelm, Proceedings of the First International Symposium on Molten Salt Chemistry and Technology, Kyoto, Japan, April, 1983; see also D. Devilliers, F. Lantelm and M. Chemla,J. Chim. Phys. 80 (1983) 267.
H. Imoto, T. Nakajima and N. Watanabe,Bull. Chem. Soc. Jap. 48 (1975) 1633; see also P. Cadman, J. D. Scott and J. M. Thomas,Surface Sci. 15 (1977) 75.
A. J. Rudge, in ‘Industrial Electrochemical Processes’ (edited by A. T. Kuhn), Elsevier, Amsterdam (1971) Chap. 1.
N. Watanabe, M. Ishii and S. Yoshizawa,J. Electrochem. Soc. Jap. 29 (1961) E180; see also N. Watanabe, ‘Proc. Electrochem. Soc., Electrochemistry of Carbon’ (1984) p. 536.
A. J. Arvia and J. B. de Cusminsky,Trans. Faraday Soc. 58 (1962) 1019.
N. Watanabe, M. Inoue and S. Yoshizawa,J. Electrochem. Soc. Jap. 31 (1963) 168.
D. M. Novak and P. T. Hough,J. Electroanal. Chem. 144 (1983) 121.
L. Bai and B. E. Conway, in course of publication (1988).
J. O'M. Bockris, ‘Modern Aspects of Electrochemistry’ (edited by J. O'M. Bockris), Butterworths, London (1954) Vol. 1, Chap. 4.
R. E. Meyer,J. Electrochem. Soc. 107 (1960) 847.
U.S. Patent No. 4602985 to Eldorado Resources Ltd (1986).
N. Watanabe,J. Fluorine Chem. 22 (1983) 205.
M. Chemla, D. Devilliers and F. Lantelme, Ann. Chim. France (1984) 633.
D. Devilliers, F. Lantelme and M. Chemla,Electrochim. Acta 31 (1986) 1235.
O. R. Brown, B. M. Ikeda and M. J. Wilmott,Electrochim. Acta 32 (1987) 1163.
L. Bai and B. E. Conway, Part II of this series, in course of publication; presented at the Conference “Centenary of the Discovery of Fluorine”, Paris, August, 1986.
J. S. Clarke and A. T. Kuhn,J. Electroanal. Chem. 85 (1977) 299.
B. E. Conway and L. Bai,J. Electroanal. Chem. 198 (1986) 149.
E. Kirowa-Eisner and E. Gileadi,J. Electrochem. Soc. 123 (1976) 22.
N. Watanabe, S. Matsui and M. Haruta,Denki Kaguku 43 (1975) 638.
B. Burrows and R. Jasinski,J. Electrochem. Soc. 115 (1968) 348.
H. K. Fredenhagen and O. T. Kreft,Z. Elektrochem. 35 (1929) 670.
C. S. Garner and D. M. Yost,J. Am. Chem. Soc. 59 (1937) 2738.
J. Kuta and E. Yeager, ‘Techniques of Electrochemistry’ (edited by E. Yeager and A. J. Salkind), John Wiley, New York (1972) Vol. 1, p. 141.
M. Sluyters-Rehbach and J. H. Sluyters, in ‘Comprehensive Treatise of Electrochemistry’ (edited by E. Yeager, J. O'M. Bockris, B. E. Conway and S. Sarangaspani), Plenum, New York (1984) Vol. 9, Chap. 4.
T. Nakajima, T. Ogawa and N. Watanabe,J. Electrochem. Soc. 134 (1987) 8.
Quarterly Report to Eldorado Resources Ltd from Electrochemistry Laboratory, University of Ottawa, March 1987.
D. Devilliers, M. Vogler, F. Lantelme and M. Chemla,Analyt. Chim. Acta 153 (1983) 69.
J. S. Hammond and N. Winograd, in ‘Comprehensive Treatise of Electrochemistry’ (edited by R. E. White, J. O'M. Bockris, B. E. Conway and E. Yeager), Plenum, New York (1984) Vol. 8.
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Bai, L., Conway, B.E. Electrochemistry of anodic F2 evolution at carbon electrodes: Bubble adherence effects in the kinetics at rotating cone electrodes. J Appl Electrochem 18, 839–848 (1988). https://doi.org/10.1007/BF01016039
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DOI: https://doi.org/10.1007/BF01016039