The Effect of Weak Adsorption on the Double Layer Capacitance

Abstract

Motivated by recents results for the double-layer on Pt(111), I reexamine the theory of weak adsorption on double-layer properties, and use it to explore the capacitance at low electrolyte concentrations. Even a very weak adsorption enhances the double layer capacitance, so that it may exceed the value CGC predicted by Gouy-Chapman theory. A Parsons-Zobel plot of (Formula presented.) vs. (Formula presented.) for the experimental capacity C does not result in a straight line of unit slope, but roughly follows a linear relation with smaller slope. These results are in line with older data on Ag(111), and with the new data on Pt(111).