Oxygen On-Demand: Understanding the Oxygen Reduction Reaction (ORR) Performance Enhancement of Conductive Polymer Films upon Modification with ZIF-8 MOF

Abstract

Recent developments surrounding the oxygen reduction reaction (ORR) focus on low-cost alternatives to materials used in traditional electrodes, e. g. Pt. To accumulate competitive advantages, these non-traditional electrodes often consist of multiple functional coating layers. Considering that each layer can potentially alter the reaction mechanism, thus changing its technological value, it becomes relevant to study how a particular electrode architecture impacts on the considered reaction pathway. From kinetic studies with rotating disk electrodes (RDE) it was found that, for Au electrodes coated with the conductive polymer P(ABA−ANI), either bare or modified with ZIF-8 (MOF) microcrystals, the ORR occurs (at neutral pH) via an associative pathway, involving a two-electron transfer process and H2O2 production. Although ZIF-8 lacks catalytic activity towards the ORR, its passive role as an in situ O2 reservoir not only enhanced the measured current response, but also extended the region of electrochemical potential under kinetic control.