Tailoring Electropolymerized Poly(3,4-ethylenedioxythiophene) Films for Oxygen Reduction Reaction

Oxygen reduction reaction (ORR) is a critical process for several electrocatalytic and photocatalytic devices. Poly(3,4-ethylenedioxythiophene), PEDOT, is an efficient ORR catalyst, with hydrogen peroxide (H2O2) being the primary reaction product. Although H2O2 is a green fuel for batteries and fuel cells and used as an industrial oxidant, it is toxic for living systems. As such, its production should be limited when PEDOT films are used in bioelectronic devices. In this work, the ORR behavior of a series of electropolymerized PEDOT films is investigated. By varying the counterion (monomeric vs polymeric), including a hydroxyl-terminated EDOT monomer in the polymer architecture, or adding a conductivity enhancer in the reaction mixture, the authors aim to understand the parameters governing the ORR properties. It is that the polymer's pristine doping level—influenced by counterion type and the presence of the conductivity enhancer—controls the ORR pathway in PEDOT films. High levels of intrinsic doping led to films with H2O2 as the major ORR product. This work suggests strategies for the design of conducting polymers with optimized performance for electrocatalytic applications and minimized production of harmful chemicals for bioelectronic devices.