The role of silver in enhancing the electrochemical activity of lead and lead–silver alloy anodes

Abstract

The role of silver as an alloying additive to reduce the overpotential of the oxygen evolution reaction on lead anodes used in the electrowinning of zinc has not previously been established. This paper summarizes the results of a detailed study of the mechanism of the action of silver both as an additive to the alloy and in solution. The presence of Ag 2 O 2 in the oxide layer was confirmed on Pb electrodes anodised in sulphuric acid electrolytes containing silver ions. The enhanced electrochemical activity of PbAg alloy anodes over Pb is attributed to the presence of Ag 2 O 2 in the corrosion layer.

Corrosion Potential Modulation on Lead Anodes Using Water Oxidation Catalyst Coatings

“…An OCP measurement after polarization was 1.69 V indicating a highly polarized species, which is consistent with Ag2O2 produced at the surface of the electrode. The Ag2O2 is a mixed silver (I, III) oxide (Ag + Ag 3+ O2) layer that increases OER activity and has been observed previously on PbAg anodes [8]. Galvanostatic CP at a constant applied current density of 50 mA·cm −2 over 30 min gave a higher potential of 2.19 V. This polarization also generates the same Ag2O2 surface species, indicated by the OCP performed afterwards resting at an equilibrium potential of 1.69 V.…”

“…One challenge in this field is measuring the thermodynamic properties of anodes, since it is well documented that the surface properties of PbAg anodes change rapidly as potentials are cycled [7,13]. With the recent advances toward understanding the role of Ag in PbAg anodes [8], we devised a method using high potential electrolysis followed immediately by voltammetry that allows us to measure OCPs of functioning systems. This method is sensitive to detect the improvement a catalyst makes to the system's oxygen evolution rate, as evidenced by the Co 2+ and Mn 2+ experiments.…”

“…In the commercial production of zinc by electrowinning, ZnO is dissolved in a sulfuric acid electrolyte, and pure Zn metal is cathodically deposited on aluminum metal cathodes. Lead-silver (PbAg) alloys are a common industrial anode for Zn electrolysis, as Ag is known to aid in protective lead dioxide (PbO 2 ) growth, lower overpotential, improve electrode conductivity, and reduce corrosion [8]. In zinc electrowinning, Mn 2+ is additionally used to minimize lead anode corrosion.…”

Regeneration of manganese electrolyte during continuous electrolysis of manganese coatings

“…Four Pb-1%Ag alloy plates [21][22][23] coated with a MnO 2 film [24] were used as inert anodes. Such anodes are widely used in industry for electrodeposition of Mn and its alloy with Ni and Zn [25][26] coatings.…”

Polarization behavior of Pb–Co powder-pressed alloy for electrowinning

“…2,3 At present, the Pb-Ca-Sn (for copper) and Pb-Ag (for zinc) alloys have been widely used as insoluble anode for oxygen evolution in EW, but it also has some limitations such as high power consumption due to the high oxygen evolution overpotential (OEOP), high manufacturing cost, unsatised mechanical strength and corrosion resistance. [4][5][6][7] In addition, for the Pb-Ag anodes, oxygen evolution reaction (OER) occurs preferentially on the Ag 2 O 2 sites on the anode surface, 8 causing the consumption of Ag. Meanwhile, various ternary alloys and quaternary alloys have been researched, but so far only Pb-Ag-Sn-Co alloy presents relatively good corrosion resistance and oxygen evolution activity.…”