The adsorption of trifluoromethanesulfonate anions at the mercury/electrolyte interface

✍ Scribed by E.R. Gonzalez; S. Srinivasan

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 425 KB
• Volume: 27
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(82)80033-9

✦ Synopsis

Recently, there has been muchinterest in the useof trifluoromethanesulfonic acid as anelectrolyte in advanced fuel cell systems because of the enhanced rate of oxygen reduction in this medium. In order to elucidate this characteristic from a double layer point of view, the present work was undertaken to study the adsorption of trifluoromethanesulfonate ions on mercury electrodes. Differential capacities and potentials of zero charge were measured in constant ionic strength solutions of composition X M CFSSOj K + (1 -X) M KF at 25°C. Analysis of the results shows that the extent of specific adsorption of CF,SO; anions is smalt, and the anions even desorb from the surface at sufficiently positive electrode charges. The structure of the inner layer is elucidated, and an isotherm for the adsorption of CF,SO, based on electrostatic models of the double layer is derived. The results indicate that at the potentials for the electroreduction of oxvxen CF,SO;

anions will not interfere with the adsorption of the reactant and of intermediates, allowing faster rates to be achieved.