Electrolyte design for high hydrogen peroxide production rates utilizing commercial carbon gas diffusion electrodes
Jessica Hübner, Gina Ruland, Florian Pietschmann, Zita Brejwo, Benjamin Paul, Peter Strasser
Abstract
The electrolyte design plays a key, yet underexplored, role in the two-electron oxygen reduction reaction (2e − ORR) to hydrogen peroxide (H 2 O 2 ). Here, we investigate the dramatic beneficial impact of alkali metal cations (AMCs) on the H 2 O 2 production in commercial carbon gas diffusion electrode-based flow electrolyzers in single-pass and closed-loop modes using online analytics. We demonstrate previously unavailable single-pass H 2 O 2 production rates of up to 123 mg cm −2 h −1 with a Faraday efficiency (FE) of 96.9% at −200 mA cm −2 in the presence of potassium cations, exceeding the corresponding production rate and FE in 0.1 M H 2 SO 4 by a factor of 34. Additionally, to the increased selectivity, the onset potential of the 2e − ORR shifted by 0.42 V toward a less negative potential. Furthermore, we explore and quantify the influence of multivalent metal cations (Ca 2+ , Mg 2+ , and Al 3+ ) on the 2e − ORR.