Electroactivity of PIPO nitroxide radical polymer films

Abstract

Nitroxide radical polymers (NRPs) are widely used as electroactive materials in a range of electrochemical applications, however, their preparation can be complex. Polyamine Immobilised Piperidinyl Oxyl (PIPO) is a commercially available, well-defined, NRP whose electrochemical properties have not been explored to date. Cyclic voltammetric (CV) studies demonstrate the electroactivity of PIPO in a range of organic electrolytes, displaying quasi -reversible redox waves, characteristic of a nitroxide radical / oxoammonium couple, with midpoint potentials in the range of 0.2 to 0.3 V vs. Fc + / Fc. When immobilised at a graphite electrode surface, PIPO maintains its electroactivity, forming stable, swellable films in acetonitrile-based electrolyte. Voltammetric and potentiometric analyses indicate that films can undergo repeated charge / discharge cycling, possibly facilitated by a diffusional controlled ‘electron hopping’ process. Furthermore, CV studies indicate that PIPO is an effective surface confined electrocatalyst for oxidation reactions of relevance to organic electrosynthesis and to lithium-air battery development. Such insights establish the basis for further investigations of PIPO as an accessible, cost-effective, and adaptable electroactive material for electrocatalytic and energy storage applications.