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electrolyte interface
J. Electroanal. Chem., 157 (1983) 151--158
151
Elsevier Sequoia S.A., Lausanne - - Printed in The Netherlands
Preliminary note
ISOMERIC P O L Y C A R B O X Y L I C IONS E F F E C T ON DOUBLE L A Y E R CAPACITY O F THE M E T A L / E L E C T R O L Y T E I N T E R F A C E :
EDWARD
DUTKIEWICZ and PIOTR SKO~,UDA
Department of Electrochemistry, Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznafi (Poland) (Received 1st August 1983)
INTRODUCTION
In an earlier paper [ 1] the stereoisomeric effect of dicarboxylic ions has been discussed in terms of the dependence of the double layer capacity on potential electrode. The results were concerned with the temperature effect, base electrolyte, as well as the effect of two stereoisomeric ions, trans (fumarate) and cis (maleate), present in aqueous solution. The influence of the intraionic hydrogen bond of the hydrogen succinate ion on the capacity h u m p has also been considered. In this paper the effect of polycarboxylic ions on the capacity versus potential has been extended to ions like: methylfumarate, methylmaleate, trans- and cispropene-l,2,3-tricarboxylate* and also fumarate and maleate b u t in formamide solution. It was expected that a correlation w o u l d be f o u n d between the geometric and electric structure of a given ion and its influence on some electrical properties of the metal/electrolyte solution interface. EXPERIMENTAL
The differential capacities versus electrode potential were measured using an ac bridge with the potential controlled potentiostatically [ 2]. The capacity of the Clavilier-type gold electrode was measured b y a sweep m e t h o d with superimposed ac [3]. In all measurements a saturated calomel electrode was used as the reference electrode. The investigations were carried o u t in an air thermostat at 298 K. The salts investigated were prepared from the given acids (Merck) and sodium carbonate (POCh-Gliwice, Analar Grade). Triply distilled water was used throughout. Formamide was purified in a manner described elsewhere [4]. *The acids for preparing these sodium salts were kindly supplied b y Prof. Dr. D. D~Spp, Universit~it-GH-Duisburg, Prof. Dr. W. Knoche, Institut fiir Physikalische Chemic, Universit~it Bielefeld and Prof. Dr. W. Vielstieh, Institut fiir Physikalische Chemic, Universit~it Bonn respectively, which is gratefully acknowledged. 0022-0728/83/$03.00
© 1983 Elsevier Sequoia S.A.
152 RESULTS AND DISCUSSION
Influence of methylfumarate and methylmaleate ions Double layer capacity measurements for maleate and fumarate aqueous solutions were presented in previous papers [ 1,5]. The thermodynamic of the adsorption of fumarate at the mercury electrode was carried out [6]. It is of interest in the context of the preceding papers [1,5,6] to investigate the effect of methyl-substituted fumarate and maleate ions on the capacity-potential dependence. By the introduction of a methyl group at carbon atom " 2 " we may expect a change in the interaction of the ions with the electrode charge and/or the water dipole, which would be reflected in the capacity--potential relation. The chemical formula of methylfumarate and methylmaleate are presented below. o
~ \ / %,,~ c II o
methylfumarate
o
II o
methylmaleate
Figure 1 shows the capacity as a function of electrode potential for 0.1 mol 1-1 sodium methylfumarate and methylmaleate aqueous solutions. The capacity--potential curve for methylmaleate exhibits a small capacity hump at the electrode potential of 0.4 V against a calomel reference electrode. It is not easy to interpret the small capacity hump observed in Fig. 1. Following the explanation given in ref. 1 the capacity hump is connected with the fiat orientation of carboxylic ions. The flat orientation (fumarate) stabilizes the orientation of the water dipole at the zero charge potential with its positive end towards the metal surface whereas the perpendicular orientation of carboxylic groups (maleate) towards the electrolyte solution stabilizes the opposite orientation separating the water dipole from the metal surface. The positive polarization of the electrode in the presence of fumarate reorients the water dipole resulting the increasing of the capacity (capacity hump) which can not be in the case of maleate. The capacity for methylfumarate has no pronounced hump (Fig. 1) and is very similar to the corresponding curve for the maleate ion. This result indicates that the introduced methyl group at carbon atom " 2 " may change the orientation of the methylmaleate with its carbon chain parallel to the metal surface and with the carboxylic groups towards the electrolyte solution.
153
3C
E u LL ~9
25
\ 20
Fig. 1. Potential dependence of the differential capacity o f a mercury electrode in aqueous solutions o f 0.1 tool 1- I s o d i u m m e t h y l fumarate ( - - × - - ) and 0.1 tool 1-~ s o d i u m m e t h y l maleate (--e--).
Effect of cis- and trans-propene-l,2,3-tricarboxylate ions
Cis -and trans-propene-l,2,3-tricarboxylate ions are the next stereoisomeric pairs and can be considered as complex ions composed of maleate with succinate (cis-propene-l,2,3-tricarboxylate) and fumarate with succinate (transpropene-l,2,3-tricarboxylate). Due to the --CH2--COO-- groups at carbon atom "2" and the possibility of rotation along the - C H 2 - - C = axis the propene-l,2,3tricarboxylate ions may be considered as stereo and rotational isomers. These dynamic properties may be indicated as shown below. 0
0
!
"\~/'% C
0
!
I ~ex
H
~0
o -
-
C
cis/cis-propene-l,2,3-tricarboxylate
o!1
zC
\J
~-o
II
C
0
0
cis/trans-propene-l,2,3-tricarboxylate
154 H e n c e the cis-propene-l,2,3-tricarboxylate ion m a y exist, as an e q u i l i b r i u m involving t h e cis/cis a n d cis/trans-propene-l,2,3-tricarboxylate. A similar e q u i l i b r i u m can be ascribed t o trans-propene-l,2,3.tricarboxylate ions: 0
0
•
0
\~/%0
,I
C
0
o,z'-~\o
trans/cis-propene-l,2,3-tricarboxylate
trans/trans-propene-l,2,3-tricarboxylate
3~
3£
?
<. U
2~
X
2C
- o,5
-i,'o
E / V v~ S~E =
Fig. 2. Potential dependence,of the differential capacity of a mercury electrode in aqueous solutions o f 0.066 mol 1-1 sodium trans-propene-l,2,3-tricarboxylate (--x--) and 0.066 mol l sodium c/s-propene-l,2,3-tricarboxylate (--o--).
155 Taking into account the likelihood that the propene-l,2,3-tricarboxylate ions exist in the equilibrium forms cis/cis ~- cis/trans and trans/cis ~ trans/trans due to intra-ionic rotation as in the case of the succinate ion [1] a " p u r e " stereo cis or trans isomeric effect as found by Parsons [5] for maleate and fumarate is n o t predicted. The capacity--potential curves for 0.1 mol 1-1 sodium cis and trans-propene1,2,3-tricarboxylate aqueous solution are presented in Fig. 2. The small capacity maximum on the capacity--potential curve for cis-propene-l,2,3-tricarboxylate ion may be caused by the fact that the cis-propene-l,2,3-tricarboxylate can exist, in part, as the cis/trans-rotamer. The capacity " h u m p " on the capacity-potential curve for trans-propene-l,2,3-tricarboxylate ion is lower in comparison with the fumarate (trans form) ion itself. This means that the trans-propene1,2,3-tricarboxylate ion is, in part, in trans/cis conformation. It seems that capacity--potential dependences in the presence of cis- or transpropene-l,2,3-tricarboxylate ions can be explained in terms of the stereogeometric molecular properties and the rotational isomerism process. This interpretation is supported by the behaviour of the succinate ion and mixture of the maleate and fumarate ions at the mercury electrolyte interface [ 1]. One can n o t exclude the further possibility that the --CH2COO- group of the propene-l,2,3-tricarboxylate ions may exist in a skew (gauche) conformation. The --CH2COO- groups in trans-propene-l,2,3-tricarboxylate ion should decrease the capacity " h u m p " , in contrast, the cis-propene-l,2,3-tricarboxylate should increase it. SOLVENT AND METAL EFFECT Fumarate aqueous solution in contact with mercury exhibits a very well developed capacity hump [ 5]. On replacing water by formamide we observe that fumarate in formamide shows only a residual capacity m a x i m u m on the c a p a c i t y potential curve and that the maleate in formamide solution is very similar to the capacity--potential curve for KF in formamide (Fig. 3). We also observe the capacity m a x i m u m at the potential of - 0 . 7 5 V with respect to the saturated mercury electrode as it was found for fluoride ion [7] shown also in Fig. 3. A capacity maximum at negative potential is observed for fumarate, maleate and fluoride ions in formamide solutions at the gold electrode in Fig. 4. At the more positive potential we can see a second capacity m a x i m u m for each ion under investigation: Two capacity maxima on the capacity--potential curve were shown by Payne [8] for potassium hexafluorophosphate in N-methylacetamide and N-methylpropionamide at the mercury electrode. In both cases the positive m a x i m u m was higher than the one at more negative potentials, which is also the case for fumarate and maleate, as seen in Fig. 4. The results presented in Fig. 4 may be explained in terms of Guidelli's theory. According to Guidelli [ 9] the capacity-potential curve with t w o maxima is a result of an increase of lateral interaction between adsorbed solvent molecules. In case of specific adsorption of ion on the electrode the positive maximum is higher than the more negative one and m a y be transformed into a steep rise of the capacity curve. The approximate s y m m e t r y of the capacity--potential curve for fluoride ion indicates that the fluoride ions are n o t specifically adsorbed as is c o m m o n l y accepted.
156
30
~E v 25 b_
u
20.
15
4"~r
0
-0,5
E//Vv$ SCE
-1,0
Fig. 3. P o t e n t i a l d e p e n d e n c e o f d i f f e r e n t i a l e a p a e i t y o f a m e r c u r y e l e c t r o d e in f o r m a m i d e solu-
tions of 0.2 tool 1-~ potassium fluoride (--x--), 0.1 tool 1-~ sodium maleate (--m--) and
0.1 raol 1-1 sodium fumarate (--A--). A comparison of the capacity--potential curves of the mercury--electrolyte solution interface with that of the gold--electrolyte solution interface shows the effect of metallic phase, ion and solvent on the form of the capacity curve. The results reported in this work provide some more arguments for suggestions and interpretations known from the literature [9--14] that the shape of the capacity of the double-layer as a function of electrode potential depends upon geometric structure of an ion, electrostatic charge distribution within an ion, or the ion polarizability, orientation of an anion in the double layer region, properties of the solvent, properties of the electrode. The fact t h a t the occurrence of the h u m p can be ascribed to various factors implies that it is n o t possible, at this stage, to a t t e m p t a classification of the capacity curves based on molecular criteria. Therefore the classification based on capacity shape proposed by Parsons [10] still seems to be the most acceptable procedure. However, a fourth class of " t w o - h u m p e d capacity curves" may be introduced as reported for various N-alkylamides [8] and also for when the metal electrode is changed. There are still m a n y unsolved questions concerning the properties and structure of metal--electrolyte interfaces as a function of potential or charge of an electrode. The capacity--potential dependence is very complex and continued
157
\ ~E u 3C L
/ / 15 0,3
-0,3 --0,6 E/Vvs SCE
Fig. 4. Potential dependence of differential capacity of gold electrode in formamide solutions of 0.1 tool 1 - ' sodium fumarate ( - - ) , 0.1 tool 1- ' sodium maleate ( - - - - ) and 0.2 tool 1- i potassium fluoride (--*--); alternating signal frequency 15 Hz, sweep rate 10 mVs -~ .
investigations in this area are desirable, involving also other methods for the capacity measurements. It is hoped to reach a deeper understanding of the ~apacity--potential dependence also from the thermodynamic analysis of the specific adsorption of the ions considered here. The analysis of the adsorption is in progress and will be presented in the near future.
ACkNOWLEDGEmENTS This work was carried out within the MRI-11 project.
REFERENCES 1 E. Dutkiewicz, J. Electroanal. Chem., 90 (1978) 211. 2 J.H. Sluyters, M. Sluyters-Rechbach and I.S.M.C. Brenkel, J. Phys. Chem. N. F., 98 (1975) 435. 3 J. Clavilier, C. R. Acad. Sci. Paris Set. C, 263 (1966) 191. 4 E. Dutkiewicz and R. Parsons, J. Electroanal. Chem., 11 (1966) 196. 5 R. Parsons and J.T. Reilly, J. Electroanal. Chem., 24 (1970) App. 23. 6 M, Privat and S. Gromb, J. Chim. Phys., 75 (1978) 484.
158 7 8 9 10 11 12 13 14
B.B. Damaskin, R.V. Ivanova and A.A. Survila, Elektrokhimiya, 1 (1965) 767. R. Payne, J. Phys. Chem., 73 (1969) 3598. R. Guidelli, J. Electroanal. Chem., 110 (1980) 205. R. Parsons, Electrochim. Acta, 21 (1976) 681. W.R. Fawcett, J. Am. Chem. Soc., 82 (1978) 1385. Z. Borkowska, J. Electroanal. Chem., 79 (1977) 206. R. Parsons, Rev. Pure Appl. Chem., 18 (1968) 91. R. Payne, Progress in Surface and Membrane Science, Vol. 8, Academic Press, New York London, 1978.
151
Elsevier Sequoia S.A., Lausanne - - Printed in The Netherlands
Preliminary note
ISOMERIC P O L Y C A R B O X Y L I C IONS E F F E C T ON DOUBLE L A Y E R CAPACITY O F THE M E T A L / E L E C T R O L Y T E I N T E R F A C E :
EDWARD
DUTKIEWICZ and PIOTR SKO~,UDA
Department of Electrochemistry, Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznafi (Poland) (Received 1st August 1983)
INTRODUCTION
In an earlier paper [ 1] the stereoisomeric effect of dicarboxylic ions has been discussed in terms of the dependence of the double layer capacity on potential electrode. The results were concerned with the temperature effect, base electrolyte, as well as the effect of two stereoisomeric ions, trans (fumarate) and cis (maleate), present in aqueous solution. The influence of the intraionic hydrogen bond of the hydrogen succinate ion on the capacity h u m p has also been considered. In this paper the effect of polycarboxylic ions on the capacity versus potential has been extended to ions like: methylfumarate, methylmaleate, trans- and cispropene-l,2,3-tricarboxylate* and also fumarate and maleate b u t in formamide solution. It was expected that a correlation w o u l d be f o u n d between the geometric and electric structure of a given ion and its influence on some electrical properties of the metal/electrolyte solution interface. EXPERIMENTAL
The differential capacities versus electrode potential were measured using an ac bridge with the potential controlled potentiostatically [ 2]. The capacity of the Clavilier-type gold electrode was measured b y a sweep m e t h o d with superimposed ac [3]. In all measurements a saturated calomel electrode was used as the reference electrode. The investigations were carried o u t in an air thermostat at 298 K. The salts investigated were prepared from the given acids (Merck) and sodium carbonate (POCh-Gliwice, Analar Grade). Triply distilled water was used throughout. Formamide was purified in a manner described elsewhere [4]. *The acids for preparing these sodium salts were kindly supplied b y Prof. Dr. D. D~Spp, Universit~it-GH-Duisburg, Prof. Dr. W. Knoche, Institut fiir Physikalische Chemic, Universit~it Bielefeld and Prof. Dr. W. Vielstieh, Institut fiir Physikalische Chemic, Universit~it Bonn respectively, which is gratefully acknowledged. 0022-0728/83/$03.00
© 1983 Elsevier Sequoia S.A.
152 RESULTS AND DISCUSSION
Influence of methylfumarate and methylmaleate ions Double layer capacity measurements for maleate and fumarate aqueous solutions were presented in previous papers [ 1,5]. The thermodynamic of the adsorption of fumarate at the mercury electrode was carried out [6]. It is of interest in the context of the preceding papers [1,5,6] to investigate the effect of methyl-substituted fumarate and maleate ions on the capacity-potential dependence. By the introduction of a methyl group at carbon atom " 2 " we may expect a change in the interaction of the ions with the electrode charge and/or the water dipole, which would be reflected in the capacity--potential relation. The chemical formula of methylfumarate and methylmaleate are presented below. o
~ \ / %,,~ c II o
methylfumarate
o
II o
methylmaleate
Figure 1 shows the capacity as a function of electrode potential for 0.1 mol 1-1 sodium methylfumarate and methylmaleate aqueous solutions. The capacity--potential curve for methylmaleate exhibits a small capacity hump at the electrode potential of 0.4 V against a calomel reference electrode. It is not easy to interpret the small capacity hump observed in Fig. 1. Following the explanation given in ref. 1 the capacity hump is connected with the fiat orientation of carboxylic ions. The flat orientation (fumarate) stabilizes the orientation of the water dipole at the zero charge potential with its positive end towards the metal surface whereas the perpendicular orientation of carboxylic groups (maleate) towards the electrolyte solution stabilizes the opposite orientation separating the water dipole from the metal surface. The positive polarization of the electrode in the presence of fumarate reorients the water dipole resulting the increasing of the capacity (capacity hump) which can not be in the case of maleate. The capacity for methylfumarate has no pronounced hump (Fig. 1) and is very similar to the corresponding curve for the maleate ion. This result indicates that the introduced methyl group at carbon atom " 2 " may change the orientation of the methylmaleate with its carbon chain parallel to the metal surface and with the carboxylic groups towards the electrolyte solution.
153
3C
E u LL ~9
25
\ 20
Fig. 1. Potential dependence of the differential capacity o f a mercury electrode in aqueous solutions o f 0.1 tool 1- I s o d i u m m e t h y l fumarate ( - - × - - ) and 0.1 tool 1-~ s o d i u m m e t h y l maleate (--e--).
Effect of cis- and trans-propene-l,2,3-tricarboxylate ions
Cis -and trans-propene-l,2,3-tricarboxylate ions are the next stereoisomeric pairs and can be considered as complex ions composed of maleate with succinate (cis-propene-l,2,3-tricarboxylate) and fumarate with succinate (transpropene-l,2,3-tricarboxylate). Due to the --CH2--COO-- groups at carbon atom "2" and the possibility of rotation along the - C H 2 - - C = axis the propene-l,2,3tricarboxylate ions may be considered as stereo and rotational isomers. These dynamic properties may be indicated as shown below. 0
0
!
"\~/'% C
0
!
I ~ex
H
~0
o -
-
C
cis/cis-propene-l,2,3-tricarboxylate
o!1
zC
\J
~-o
II
C
0
0
cis/trans-propene-l,2,3-tricarboxylate
154 H e n c e the cis-propene-l,2,3-tricarboxylate ion m a y exist, as an e q u i l i b r i u m involving t h e cis/cis a n d cis/trans-propene-l,2,3-tricarboxylate. A similar e q u i l i b r i u m can be ascribed t o trans-propene-l,2,3.tricarboxylate ions: 0
0
•
0
\~/%0
,I
C
0
o,z'-~\o
trans/cis-propene-l,2,3-tricarboxylate
trans/trans-propene-l,2,3-tricarboxylate
3~
3£
?
<. U
2~
X
2C
- o,5
-i,'o
E / V v~ S~E =
Fig. 2. Potential dependence,of the differential capacity of a mercury electrode in aqueous solutions o f 0.066 mol 1-1 sodium trans-propene-l,2,3-tricarboxylate (--x--) and 0.066 mol l sodium c/s-propene-l,2,3-tricarboxylate (--o--).
155 Taking into account the likelihood that the propene-l,2,3-tricarboxylate ions exist in the equilibrium forms cis/cis ~- cis/trans and trans/cis ~ trans/trans due to intra-ionic rotation as in the case of the succinate ion [1] a " p u r e " stereo cis or trans isomeric effect as found by Parsons [5] for maleate and fumarate is n o t predicted. The capacity--potential curves for 0.1 mol 1-1 sodium cis and trans-propene1,2,3-tricarboxylate aqueous solution are presented in Fig. 2. The small capacity maximum on the capacity--potential curve for cis-propene-l,2,3-tricarboxylate ion may be caused by the fact that the cis-propene-l,2,3-tricarboxylate can exist, in part, as the cis/trans-rotamer. The capacity " h u m p " on the capacity-potential curve for trans-propene-l,2,3-tricarboxylate ion is lower in comparison with the fumarate (trans form) ion itself. This means that the trans-propene1,2,3-tricarboxylate ion is, in part, in trans/cis conformation. It seems that capacity--potential dependences in the presence of cis- or transpropene-l,2,3-tricarboxylate ions can be explained in terms of the stereogeometric molecular properties and the rotational isomerism process. This interpretation is supported by the behaviour of the succinate ion and mixture of the maleate and fumarate ions at the mercury electrolyte interface [ 1]. One can n o t exclude the further possibility that the --CH2COO- group of the propene-l,2,3-tricarboxylate ions may exist in a skew (gauche) conformation. The --CH2COO- groups in trans-propene-l,2,3-tricarboxylate ion should decrease the capacity " h u m p " , in contrast, the cis-propene-l,2,3-tricarboxylate should increase it. SOLVENT AND METAL EFFECT Fumarate aqueous solution in contact with mercury exhibits a very well developed capacity hump [ 5]. On replacing water by formamide we observe that fumarate in formamide shows only a residual capacity m a x i m u m on the c a p a c i t y potential curve and that the maleate in formamide solution is very similar to the capacity--potential curve for KF in formamide (Fig. 3). We also observe the capacity m a x i m u m at the potential of - 0 . 7 5 V with respect to the saturated mercury electrode as it was found for fluoride ion [7] shown also in Fig. 3. A capacity maximum at negative potential is observed for fumarate, maleate and fluoride ions in formamide solutions at the gold electrode in Fig. 4. At the more positive potential we can see a second capacity m a x i m u m for each ion under investigation: Two capacity maxima on the capacity--potential curve were shown by Payne [8] for potassium hexafluorophosphate in N-methylacetamide and N-methylpropionamide at the mercury electrode. In both cases the positive m a x i m u m was higher than the one at more negative potentials, which is also the case for fumarate and maleate, as seen in Fig. 4. The results presented in Fig. 4 may be explained in terms of Guidelli's theory. According to Guidelli [ 9] the capacity-potential curve with t w o maxima is a result of an increase of lateral interaction between adsorbed solvent molecules. In case of specific adsorption of ion on the electrode the positive maximum is higher than the more negative one and m a y be transformed into a steep rise of the capacity curve. The approximate s y m m e t r y of the capacity--potential curve for fluoride ion indicates that the fluoride ions are n o t specifically adsorbed as is c o m m o n l y accepted.
156
30
~E v 25 b_
u
20.
15
4"~r
0
-0,5
E//Vv$ SCE
-1,0
Fig. 3. P o t e n t i a l d e p e n d e n c e o f d i f f e r e n t i a l e a p a e i t y o f a m e r c u r y e l e c t r o d e in f o r m a m i d e solu-
tions of 0.2 tool 1-~ potassium fluoride (--x--), 0.1 tool 1-~ sodium maleate (--m--) and
0.1 raol 1-1 sodium fumarate (--A--). A comparison of the capacity--potential curves of the mercury--electrolyte solution interface with that of the gold--electrolyte solution interface shows the effect of metallic phase, ion and solvent on the form of the capacity curve. The results reported in this work provide some more arguments for suggestions and interpretations known from the literature [9--14] that the shape of the capacity of the double-layer as a function of electrode potential depends upon geometric structure of an ion, electrostatic charge distribution within an ion, or the ion polarizability, orientation of an anion in the double layer region, properties of the solvent, properties of the electrode. The fact t h a t the occurrence of the h u m p can be ascribed to various factors implies that it is n o t possible, at this stage, to a t t e m p t a classification of the capacity curves based on molecular criteria. Therefore the classification based on capacity shape proposed by Parsons [10] still seems to be the most acceptable procedure. However, a fourth class of " t w o - h u m p e d capacity curves" may be introduced as reported for various N-alkylamides [8] and also for when the metal electrode is changed. There are still m a n y unsolved questions concerning the properties and structure of metal--electrolyte interfaces as a function of potential or charge of an electrode. The capacity--potential dependence is very complex and continued
157
\ ~E u 3C L
/ / 15 0,3
-0,3 --0,6 E/Vvs SCE
Fig. 4. Potential dependence of differential capacity of gold electrode in formamide solutions of 0.1 tool 1 - ' sodium fumarate ( - - ) , 0.1 tool 1- ' sodium maleate ( - - - - ) and 0.2 tool 1- i potassium fluoride (--*--); alternating signal frequency 15 Hz, sweep rate 10 mVs -~ .
investigations in this area are desirable, involving also other methods for the capacity measurements. It is hoped to reach a deeper understanding of the ~apacity--potential dependence also from the thermodynamic analysis of the specific adsorption of the ions considered here. The analysis of the adsorption is in progress and will be presented in the near future.
ACkNOWLEDGEmENTS This work was carried out within the MRI-11 project.
REFERENCES 1 E. Dutkiewicz, J. Electroanal. Chem., 90 (1978) 211. 2 J.H. Sluyters, M. Sluyters-Rechbach and I.S.M.C. Brenkel, J. Phys. Chem. N. F., 98 (1975) 435. 3 J. Clavilier, C. R. Acad. Sci. Paris Set. C, 263 (1966) 191. 4 E. Dutkiewicz and R. Parsons, J. Electroanal. Chem., 11 (1966) 196. 5 R. Parsons and J.T. Reilly, J. Electroanal. Chem., 24 (1970) App. 23. 6 M, Privat and S. Gromb, J. Chim. Phys., 75 (1978) 484.
158 7 8 9 10 11 12 13 14
B.B. Damaskin, R.V. Ivanova and A.A. Survila, Elektrokhimiya, 1 (1965) 767. R. Payne, J. Phys. Chem., 73 (1969) 3598. R. Guidelli, J. Electroanal. Chem., 110 (1980) 205. R. Parsons, Electrochim. Acta, 21 (1976) 681. W.R. Fawcett, J. Am. Chem. Soc., 82 (1978) 1385. Z. Borkowska, J. Electroanal. Chem., 79 (1977) 206. R. Parsons, Rev. Pure Appl. Chem., 18 (1968) 91. R. Payne, Progress in Surface and Membrane Science, Vol. 8, Academic Press, New York London, 1978.