Electrosynthesis of hydrogen peroxide sustained by anodic oxygen evolution in a flow-through reactor

Abstract

This study reports the performance of a flow-through reactor to promote the sustainable production of H2O2 upon cathodic reduction of anodically generated O2. A smart configuration that alternated Ti|IrO2-Ta2O5 anode meshes, as a source of O2 subsequently reduced to H2O2 at adjacent porous reticulated vitreous carbon cathodes, was successfully tested employing a 0.050 M Na2SO4 solution at pH 3.0. With this reactor, the need of an external source of pure O2 or air typically employed during the electrosynthesis of this high value commodity was avoided. Bulk electrolyses in recirculation operation mode were carried out to evaluate the influence of the volumetric flow rate (0.4-1.0 L min-1) and applied current (59.5-178.5 mA) on the H2O2 accumulation profiles. The best performance of the reactor was achieved at 0.8 L min-1 and 59.5 mA, reaching 14.3 mg L-1 H2O2 after 3 h, with maximum current efficiency and electrolytic energy consumption of 100% and 0.021 kWh (g H2O2)-1, respectively. This is a first approach to produce greener H2O2, envisaging its future application to water treatment by electrochemical advanced oxidation processes.