Retarded electrodeposition of metals studied oscillographically with mercury capillary electrodes

Heyrovský, J.

doi:10.1039/df9470100212

Cited by 118 publications

(53 citation statements)

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“…The very small quantities of chloride ion necessary to reduce markedly the polarization in the presence of glutainic acid, together with the high rate with which the polarization is reduced, do not encourage the view expressed in previous papers that chloride exerts its influence through a corrosion type of process. An alternative suggestion is that chloride ion might facilitate electron transfer by acting as an electron "bridge", in the manner suggested by Heyrovsky (10) to account for the accelerated deposition of zinc on a mercury cathode in the presence of chloride ion. In the present system, the electron "bridges" might be assumed to facilitate electron transfer from the cathode to copper-glutamic complexes on the surface or to operate between complexes to promote their decomposition, Can.…”

Section: Discussionmentioning

confidence: 99%

Glutamic Acid as an Addition Agent in the Electrodeposition of Copper

Adamek¹,

Winkler²

1954

Can. J. Chem.

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The polarization-time curves obtained in the presence of glutamic acid generally showed two distinct polarization levels, one corresponding to an induction period following an initial rapid increase of polarization from the standard surface value, and the other corresponding to a steady state period following a second rapid increase of polarization. The polarization a t both levels increased with increase of glutamic acid concentration and decreased with increase of sulphuric acid concentration in the electrolyte. In general, the induction period increased, and eventually became irreproducible, with increased sulphuric acid and copper sulphate concentrations, decreased gluta~nic acid concentration, decreased current density, increased temperature, and addition of chloride. Addition of sufficient chloride prolonged the induction period indefinitely at a polarization level corresponding to the presence of chloride alone. Following the induction period, the concentration polarization increased with glutamic acid concentration and was considerably higher than the value obtained during the induction period. Addition of chloride decreased the concentration polarization. INTRODUCTIONSeveral previous papers from this laboratory have discussed the changes in cathode polarization during the deposition of copper when gelatin alone, or gelatin plus chloride ion, are present as addition agents in the electrolyte (5,6,12,14). The increase in polarization observed in the presence of gelatin alone has been interpreted as a consequence of an increase in true current density when the active area of the cathode is reduced by adsorption of gelatin. A marked decrease in polarization below the value observed with gelatin alone, when small quantities of chloride ion (of the order 2 mgm. per liter) are added with the gelatin, was attributed to an increase of active area by attack of the halide ion on less active parts of the cathode surface.A recent study of the initial changes in cathode polarization (13) has shown that, in the presence of gelatin but not in its absence, these changes were dependent upon the time the cathode was in contact with the electrolyte before electrolysis was begun. There was just a suggestion from this behavior t h a t corrosion processes, with accompanying formation and adsorption of coppergelatin complexes, might play a significant part in the addition agent effect of gelatin. Other workers have concluded that substances which function as addition agents form conlplexes with metal ions in the solution (3, 4, 7-9, 11).T o obtain,'further information about the way in which con~plex formation might be concerned in the mechanism of addition agent action, it seemed reasonable to study the behavior of a simple amino acid, rather than gelatin, as the addition agent. The ability of many such acids to forin heavy metal complexes is well recognized, and copper complexes with several of them have been isolated. I t was also hoped that further study of the effect of chloride ion, 'i\fanziscript

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Section: Discussionmentioning

confidence: 99%

Glutamic Acid as an Addition Agent in the Electrodeposition of Copper

Adamek¹,

Winkler²

1954

Can. J. Chem.

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“…In recent years, however, evidence has accumulated which indicates that the anions contribute directly to the discharge reactions and to the formation of metallic ions (8)(9)(10)(11)(12)(13)(14).…”

Section: Anion Concentration and Dissolution Rates--mentioning

confidence: 99%

Effects of Anions on the Dissolution Kinetics of Metals

Kolotyrkin

1961

J. Electrochem. Soc.

173

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In acidic solutions CI-, Br-, and I-ions increase the true anodic dissolution rate of cadmium and of indium amalgam considerably. This is accounted for by the direct participation of these ions in elementary processes of ionizing metal atoms. The chemoadsorptive interaction of halide ions with surface atoms of a metal takes place at potentials much more negative than the dissolution potential of the metal. The extent of "filling" the surface with adsorbed anions increases considerably with shift of potential to more positive values. Some concepts are developed about the mechanism of dissolution of metal with direct participation of the solution components. These concepts explain both the dissolution rate acceleration by ions that specifically adsorb and the passivation of a metal surface by adsorbed oxygen from water.The mechanism of formation and development of pits on the surface of a corroded metal has been considered, zirconium dissolution in chloride, bromide, and iodide solutions being an example. It is postulated that a necessary condition for formation of pits is a greater affinity of the corroded metal for oxygen than for the attacking anion and that formation of pits is a result of the substituted adsorption of halide ions for passivating oxygen at certain sites on the metal surface.The dissolution of metals in electrolytic solutions is, by its nature, an electrochemical process, and its rate depends not only on the usual variables of chemical kinetics, concentration and temperature, but also on these electrochemical parameters of the system and, first and foremost, on the electrode potential and the structure of the electric double layer at the metal-solution boundary.According to the laws of electrochemical kinetics, the dependence of the dissolution rate on the potential, in the simplest case, can be expressed by il = KI" exp (flF/RT~) [1] where il is the dissolution rate in terms of electric current, r is the electrode potential, fl is the transfer coefficient, and K1 is a constant depending on the metal and its surface condition.Equation [1] holds for a process which can be expressed generally by Me-~ Me*" -]-ne [2] In the case of the spontaneous dissolution of metal in acid, reaction [2] is accompanied by simultane~ ous cathodic hydrogen evolution 2H + -~ 2e-> H_~ [3] the kinetics of which can be expressed by i2 = K_~ [H +] 9 exp (--~ F/RT ~) [4] Combining [1] and [4], the dependence of the spontaneous dissolution rate of the metal on the acid concentration is given by the equation V = Ko [H+] ~~ [5]which, in a number of cases, is borne out by experi- ments (1-3). Anion concentration and dissolution rates.--There are, however, many cases when the dissolution rate of metals in acid solutions depends not only on the concentration of hydrogen ions directly participating in the process, but also on the nature and concentration of anions which, at first sight, do not seem to take part. Recent research in this laboratory has shown that changes in the anion composition can influence both the cathodic (hy...

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“…If the supporting electrolyte contains some anions which form complexes with bismuth ions, the reduction rate of Bi III may be significantly increased [8,12]. The influence of chloride ions on the rate of electrochemical reduction of bismuth ions on mercury electrodes was noticed by Heyrovsky almost forty years ago [1]. In addition, it will be shown that Br ¹ and I ¹ ions influence the reduction rate of Bi III more strongly than Cl ¹ ion because these ions form stronger complexes with Bi III than Cl ¹ ion [8].…”

Section: Introductionmentioning

confidence: 98%

“…The polarographic reduction of bismuth III ions on a mercury electrode in 1 mol dm ¹3 HClO 4 is irreversible [1][2][3][4][5][6][7][8][9]. They are three successive one-electron charge-transfer steps [4,7].…”

Section: Introductionmentioning

confidence: 99%

The Catalysis of the Reduction of BiIII Ions by Methionine

Sykut

Dalmata

Nieszporek³

1998

Electroanalysis

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A multistep reduction of Bi III ions at the dropping mercury electrode in 1M HClO 4 with the addition of methionine was examined using an impedance method in wide potential and frequency ranges. It was found that the standard rate constants and the rate constants of the first electron transfer increase with the concentration increase of methionine. The rectilinear relation k f ¼ f(G) indicates formation of Bi-methionine bridges which facilitate the transfer of electrons across the inner layer.

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Retarded electrodeposition of metals studied oscillographically with mercury capillary electrodes

Cited by 118 publications

References 0 publications

Glutamic Acid as an Addition Agent in the Electrodeposition of Copper

Glutamic Acid as an Addition Agent in the Electrodeposition of Copper

Effects of Anions on the Dissolution Kinetics of Metals

The Catalysis of the Reduction of BiIII Ions by Methionine

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