Potentiostatic passivation of zinc in alkaline solutions

Cabot, Pere Lluı́s; Cortés, M.; Centellas, Francesc; Pérez, E.

doi:10.1007/bf00296694

Cited by 18 publications

(17 citation statements)

References 29 publications

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“…This indicates that the diffusion of NAD þ most likely does not occur in the solution, but rather could be considered as the surface diffusion. Similar or even lower values, related to the surface diffusion of electroactive species, are quite common in the fuel cell electrocatalysis on Pt-Ru surfaces [36][37][38], where CO adsorbed on Pt sites is being oxidized by oxygen-containing species diffusing from neighboring Ru sites, or in electrocrystallization of new phases [39][40][41][42]. More similarly to the NAD þ molecule, surface diffusion of N -butyl-3-(hydroxynonyl)pyridinium was recorded as a slow step in adsorption on a platinum electrode [43], while a value of 4.5 Â 10 À8 cm 2 s À1 was reported for diffusion of tetramethylsilane on Ru [44].…”

Section: Cyclic Voltammetrymentioning

confidence: 98%

A kinetic study of NAD+ reduction on a ruthenium modified glassy carbon electrode

Man

Omanovic

2004

Journal of Electroanalytical Chemistry

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Section: Cyclic Voltammetrymentioning

confidence: 98%

A kinetic study of NAD+ reduction on a ruthenium modified glassy carbon electrode

Man

Omanovic

2004

Journal of Electroanalytical Chemistry

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“…Over the years, several investigations have analyzed the properties of the passive film and the anodic passivation mechanism in alkaline solution . The passivation of the zinc electrode takes place when the dissolution of zinc induces an excessive concentration of the hydroxide or salt in the electrolyte close to electrode, surpassing the solubility limit that promotes the precipitation and formation of a compact film .…”

Section: Problems Associated To the Zinc Anodementioning

confidence: 99%

Alkaline aqueous electrolytes for secondary zinc-air batteries: an overview

Mainar

Leonet

Bengoechea

et al. 2016

Int. J. Energy Res.

261

192

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Summary New applications and emerging markets in electromobility and large‐scale stationary energy storage require the development of new electrochemical systems with higher energy density than current batteries. Rechargeable metal–air batteries, mainly lithium–air and zinc–air systems, are considered one of the most promising candidates. In contrast to lithium, zinc is abundant, inexpensive and its electrodeposition in aqueous electrolytes is relatively easy. Unfortunately, achieving a rechargeable zinc–air battery is still hindered by various technical problems related to the reversibility and lifetime of the electrodes. The most widely used electrolyte in zinc–air batteries has been the classical aqueous alkaline. In this context and with the main objective of providing a complete overview, we studied a wide number of articles starting from the beginning of the development of secondary zinc–air batteries (1970–1980s) to more recent works, with the aim of compiling all available information. It is essential to revise older papers to find relevant information that may get otherwise forgotten and not taken into account to develop new solutions. This information could also be applied in other storage systems based on zinc as nickel–zinc, zinc hybrid or zinc‐ion. Copyright © 2016 John Wiley & Sons, Ltd.

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“…. Zinc anode passivation [37,38] due to saturation of the surface by ZnðOHÞ 2À 4 and ZnðOHÞ À 3 forming a solid film progressively converted to ZnO 1Àx (OH) 2x , OH À doped ZnO, and finally Zn-doped ZnO. This can be solved by solution agitation and by choosing not too high a value for the anode current density.…”

Section: Alkaline Noncyanide Zinc Bathsmentioning

confidence: 99%

Electrodeposition of Zinc and Zinc Alloys

Winand¹

2010

Modern Electroplating

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Zinc has a standard reversible potential [À0.76 V/standard hydrogen electrode (SHE)] that is more negative than that of iron (Fe/Fe 2 þ -0.44V/SHE). For this reason zinc is used for sacrificial cathodic protection of steel against corrosion.According to Fischer [1], in metal electrodeposition, zinc can be considered as an intermediate metal, giving rise to medium values of overpotentials due to secondary inhibition resulting from adsorbed hydrolized species.In acid sulfate solutions without an organic additive, BR metallographic cross-sectional structures are obtained (BR: basis reproduction; coherent deposits with coarse crystals whose diameter increases with the deposit thickness; see Fig. 10.1). In chloride electrolytes, even coarser grains are observed, because of the more activating character of chloride ions against sulfate ions [2] and despite the complex formation in solution [3, p. 464]. In cyanide baths, on the other hand, much finer grains are obtained, and the deposits pertain to the FT (field-oriented texture: coherent deposits, with elongated crystals perpendicular to the substrate, with almost constant diameter throughout the deposit thickness) or UD types (UD: unoriented dispersion type; coherent deposit, with small crystals showing three-dimensional nucleation to occur all the time during electrodeposition). Figure 10.2 shows a deposit obtained in a cyanide solution without an organic additive: the structure is initially FT, but it becomes progressively bad. Going from a cyanide bath to a noncyanide alkaline bath should result in still worse deposits because electrolyte complexation decreases [3] and exchange current density increases [4, pp. 528-543].Accordingly, when rather thick deposits are needed and/or if a bright surface is required, organic additives are always present at high concentration (1 g L À1 or more). This always occurs in barrel-and-rack plating of small pieces of equipment, because the local current densities will vary over a wide range. For continuous plating on steel sheets or wires, constant current density and rather good hydrodynamic control may be achieved over the whole cathodic surface, and organic additives are not so much in use.Whatever the pH, zinc is always more negative than hydrogen [5]. In electrolytes where zinc is complexed, its standard reversible potential is still more negative; for instance, for cyanide baths, the reversible potential for reactionin alkaline solution is À1.26 V/SHE [6]. Consequently hydrogen evolution occurs at the cathode as a competitor to zinc deposition, resulting in a decrease of current efficiency and eventually in some atomic hydrogen diffusion into the substrate.Finally, in industrial processes electrolytic plating is an alternative to hot-dip galvanizing. Both processes have advantages and disadvantages. Continual technological improvements make it difficult to conclude in favor of one process over the other. However, hot dip always includes some surface alloying by diffusion, and the deposit thickness is less easily controlled th...

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Potentiostatic passivation of zinc in alkaline solutions

Cited by 18 publications

References 29 publications

A kinetic study of NAD+ reduction on a ruthenium modified glassy carbon electrode

A kinetic study of NAD+ reduction on a ruthenium modified glassy carbon electrode

Alkaline aqueous electrolytes for secondary zinc-air batteries: an overview

Electrodeposition of Zinc and Zinc Alloys

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