Crossover Understanding of a Hydrogen Peroxide Electrosynthesis Device By Combining Oxygen Reduction and Organics Oxidation Reaction

Abstract

Hydrogen peroxide (H2O2) is a highly useful and green liquid chemical for daily life and industry. It is traditionally employed in wood industry, food packaging, fine chemicals synthesis and environmental depollution. Moreover, it is recently considered in the context of energy storage and conversion such as metal–hydrogen peroxide batteries since the world is trying to find high energy density batteries to replace lithium-ion batteries for electric vehicles and electrified aircraft [1].Electrochemical production of H2O2 driven by cheap renewable electricity has emerged recently as an alternative to non-sustainable anthraquinone oxidation (AO) process. The recent surge of H2O2 electrosynthesis studies is mainly focused on advanced H2O2 production catalyst design aiming at achieving high activity and selectivity during the last couple of years [2]. As an essential part of H2O2 electrochemical reactors, anode reaction/process is given very little attention among investigators until recently. Water oxidation is the most used anodic reaction, but it suffers from high energy input, the use of expensive catalyst, and low-priced oxygen gas generation. This problem might be mitigated by using alternative organics oxidation processes with the possible generation of value-added products [3]. In order to be economically viable for these systems above, the organics in anode reservoir should not transport to the cathode part through the membrane. However, organic molecules crossover has already been identified in direct alcohol fuel cells and CO2 electrolyzers. Such organics crossover, to the best of our knowledge, has never been considered in previous reports on hydrogen peroxide electrosynthesis devices.We use conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) for ORR via a two-electron pathway to H2O2. 4,5-Dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate (BQDS) was used as a model organic molecule since its oxidation process does not require catalysts as a typical electrolyte used in redox flow batteries. We investigated electrolyte and electric field effects on crossover and H2O2 production.[1] Chem Catal. 2023, 3, 100568[2] Nat. Rev. Chem.2019, 3, 442[3] Nat. Energy 2021, 6, 904