Effect of Supporting Electrolyte on Mass Transport through Nafion Films

Abstract

The role supporting electrolyte plays on the transport of the redox probe tris(bipyridine)ruthenium(II) chloride through the ion exchange polymer Nafion® was examined using cyclic voltammetry, rotating disk voltammetry, and spectroscopic techniques. Variations in both the extraction coefficient (κ) and the diffusion coefficient (D) were observed as the supporting electrolyte was varied. The anion of the supporting electrolyte was not found to influence mass transport, but the cation significantly influenced both extraction and diffusion of the redox probe within the polymer. A series of monovalent (Li+, Na+, K+, Rb+) and divalent (Mg2+, Ca2+, Ba2+, Zn2+) cations were studied, as well as the trivalent cation La3+.