Migration-mitigated crossover of organic redox anions across a proton-exchange membrane†

The two-electron oxygen reduction reaction (ORR), powered by affordable renewable energy, presents a more promising and sustainable approach to hydrogen peroxide production than traditional methods. In this study, we introduce a membrane electrolyzer for ORR-to-H₂O₂ generation. The conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) acts as the cathode that aids the oxygen reduction reaction through a two-electron pathway to produce H₂O₂. At the anode, we employed the oxidation of a model organic molecule, 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate (tiron). This catalyst-free anode process, as an alternative to the sluggish water oxidation reaction commonly used in classical electrolyzers, reduces voltage loss to release protons, cross the membrane, and feed the ORR at the cathode. Our study investigated the often-neglected issue of organic crossover during electrolyzer operation and its significant impact on transport behavior. This research paves the way for the development of crossover-free flow cells, extending the realm of electrochemical devices based on the electrolyte fed and the membrane.