Perfluoro-Functionalized Conducting Polymers Enhance Electrocatalytic Oxygen Reduction

Abstract

In this study, films of perfluoro-functionalized poly(3,4-ethylenedioxythiophene) [poly(EDOT-F)] were prepared directly through electropolymerization for use as catalysts for the oxygen reduction reaction (ORR), applying the rotating ring disk electrode technique. Poly(EDOT-F) operated catalytically through a two-electron and/or mixed pathway. Spinel Co3O4 nanospheres were introduced into poly(EDOT-F) to enhance its ORR performance and electron transfer number (n). Benefiting from its unique interconnected pore structure and its resemblance to the binder Nafion, poly(EDOT-F) could be used as a single replacement for both the binder and the carbon support required for the spinel Co3O4 nanospheres. The Co3O4/poly(EDOT-F) composite, when used as an electrode, exhibited a limiting current density of -4.761 mA cm(-2) at 0.18 V (vs RHE) (cf. 20% Pt/C: -3.615 mA cm(-2)), an onset potential of 0.99 V (cf. 20% Pt/C: 0.938 V), and a half-wave potential of 0.628 V (cf. 20% Pt/C: 0.727 V) in 0.1 M aqueous KOH. The electron transfer number of the Co3O4/poly(EDOT-F) nanocomposite in the ORR was 3.84, suggesting a desirable four-electron pathway. This high electrocatalytic activity presumably resulted from the synergistic effect of the Co3O4 nanospheres and the poly(EDOT-F) polymer, which created many more active sites, enhanced the electron transfer kinetics, and eventually improved the ORR performance.