Modeling the electrosynthesis of H2O2: Understanding the role of predatory species

Abstract

In this work, the electrosynthesis of hydrogen peroxide from the oxygen reduction reaction is evaluated using a flow-by electrochemical cell under different operation conditions and electrodes. In addition, a phenomenological model is proposed to understand the processes that occur inside the electrochemical reactor, and how the predatory species act against the production of H2O2 at high concentrations. In comparing different types of anodes, the electrosynthesis of H2O2 is almost twice as efficient when using DSA-Cl2 instead of BDD as the anode, which allowed it to reach concentrations as high as 4.2 g L‾1. The rate of decomposition of H2O2 is higher when the more vigorous anode is used. This decomposition is not only caused by the H2O2 on the anode surface or by its self-decomposition within the bulk, but it is mostly related to the electrochemical processes of production of H2O2′s predatory species such as ozone and peroxymonopersulfate. The formulated phenomenological model explains and satisfactorily reproduces the influence of anode type, electrolyte, and current density on the electrosynthesis of H2O2 at high concentrations obtaining regression coefficients higher than 0.99.