Anodic generation of hydrogen peroxide in continuous flow

Abstract

The electrochemical production of hydrogen peroxide (H₂O₂) is an appealing green alternative to the classic anthraquinone process. Herein, we show the development of a process to produce H₂O₂ anodically in continuous flow at high current densities. The role of CO₃²⁻ ion activity in enhancing the anodic H₂O₂ generation using a commercial boron-doped diamond (BDD) electrode is investigated in detail. The process development comprising the optimization of electrolyte flow type and flow rates enabled electrochemical operation at current densities up to 700 mA cm⁻², with Faraday efficiencies up to 78%, and the highest-ever reported H₂O₂ production rate of 79 μmol min⁻¹ cm⁻². Continuous flow experiments are essential for technical applications, which is one of the first upscaling steps. A continuous and stable H₂O₂ productivity with constant production rates for up to 28 hours was achieved. Our experiments unfold the importance of electrochemical process development and the interplay of the electrode, electrolyte, and operating cell parameters to achieve a highly efficient, scalable, stable, and continuous system for the 2e⁻ water oxidation to H₂O₂.