Conductivity of Anodic Silver Chloride during Formation

Abstract

Silver electrodes were anodized in normalKCl , normalNaCl , normalLiCl , and normalHCl solutions of concentration greater than 4N. High field conduction was exhibited by the growing normalAgCl film during the anodizing process at current densities greater than 1 mA/cm2. The high field barrier film reverts to a porous high conductivity film at applied potentials greater than 20V or when the anodizing current is interrupted or briefly reversed.

Microstructure, surface chemistry and electrochemical response of Ag|AgCl sensors in alkaline media

“…Surface chemistry, microstructure and ohmic resistance of the AgCl layer Except the above-discussed aspects in relation to overpotential and surface of the sensors, abnormal overpotential evolution would be attributable to an increase in thickness but also, in general, reflecting an increase in ohmic resistance of the surface layer [8]. The ohmic resistance, however, is a combination of both ionic and electron resistance.…”

“…Eventually, the blockage and reduced number of micro-channels will increase the tortuosity and the transport distance of ions within the layer. At this stage, a sequence of incipient ''crack'' formation and ''healing'' of the already available cracks occurs [8]. The cracks are actually a slight broadening of the micro-channels, already existing in the layer.…”

“…While the sensor's response is just a common open-circuit potential (OCP) record, i.e., the Ag/AgCl electrode potential reading, the possible discrepancies will reflect the time needed for establishing a dynamic equilibrium at the sensor/environment interface. Although fundamental electrochemical thermodynamics and kinetics can explain these discrepancies [4][5][6][7][8][9][10][11][12], practical application of the Ag/AgCl sensors for RC structures is still to be justified. This justification refers to specifying the limits for these sensors' application and the reasons behind the existence of such limits.…”

“…The thermodynamic considerations and the kinetics of AgCl formation on a Ag substrate were subject to numerous works in the fields of electrochemistry and crystal growth since the early 1950s [5][6][7][8][9][10][11]. Despite the results in these thoroughly elaborated works, the properties and performance of Ag/AgCl electrodes in the alkaline medium are yet to be affirmed, especially in view of their application as chloride sensors for RC structures.…”

Electrode kinetics in the “capacitive mixing” and “battery mixing” techniques for energy production from salinity differences

“…The electrode is covered by silver chloride by means of anodization, that is performed at 3 mA in a 3 M sodium chloride solution for 1 hour [37,38,39].…”