Anodic behavior of silver in alkaline solutions

Abstract

Data, covering a range of pH and temperature, were obtained for the anodic oxidation of electropolished silver and the results compared with electrodes which had undergone repeated oxidation and reduction cycles. The behavior of the electrode is, in the main, complex, showing, for example, autopotential cycling under certain galvanostatic conditions (-3 pA/cmZ, 25 "C, 0.7 N NaOH), the period of oscillation being about t h. Several other hitherto unreported phenomena were also observed. The main conclusions reached are (i) that 2 different mechanisms are involved in the anodic formation of AgzO on silver electrodes in basic electrolytes resulting in 2 types of film, 1 mechanism involves a dissolution-precipitation process, the other possibly a direct interfacial reaction; (ii) that the reduction of anodically formed Ag,O films either electrochemically or in hydrogen at 800 OC leaves behind a highly porous,layer of silver metal; and (iii) that the limiting AgzO film thickness is probably determined by a diffusion process occurring within the film.

Anodic Behavior of Silver in Alkaline Solutions

“…5. The intersection of the two lines falls near 0.25 mA cm -2, the current density noted by Dignam et al (5) to be unique. The experimental points in Fig.…”

“…Its growth is terminated rather abruptly with the rapid increase of electrode potential to be followed by the formation of AgO and possibly higher oxides, before oxygen is eventually evolved. It was found that the kinetic behavior of silver electrodes was profoundly influenced by surface conditions (5) and it would thus seem that further studies should be carried out on smooth well-defined surfaces. This paper is concerned primarily with the investigation of the initial electrode process, namely the formation of Ag20.…”

Nucleation of Silver (I) Oxide Investigated by Spectroscopic Ellipsometry

“…Typical polarization curves for galvanostatic oxidation [18,19,29,30J show a rising potential that peaks and then shows a shallow dip. Figure 5 shows potential measurements corresponding to the optical measurements shown in figure 4.…”

Electrochemical formation and reduction of silver oxides in alkaline media

“…In the charging situation, the Ag/Ag20 plateau does not persist as long as the Ag20/AgO level, especially at higher current density [24,32,34,35,41,43]. This has led to the conclusion that the layer of AgO is thicker than that of Ag20 [2,3,4,7].…”