High effective generation of hydrogen peroxide by adjusting three-phase interfaces of gas diffusion electrode during the oxygen reduction reaction

Abstract

Mass transfer of oxygen is a critical issue in the two-electron oxygen reduction reaction (2e− ORR) for the generation of hydrogen peroxide (H2O2). In this study, a novel constant velocity gas diffusion electrode (CVGDE) that can control the gas flow rate through the catalyst layer was fabricated, and the effect of the gas flow rate on three-phase interfaces (TPIs) formation and the mass transfer of oxygen in gas diffusion electrode (GDE) was investigated. In CVGDE, oxygen mass transfer was significantly improved, and the yield of H2O2 reached up to 73.65 mg cm−2 h−1 at 200 mA cm−2, which was 74.3 % higher than that of conventional GDE. Furthermore, the oxygen utilization efficiency of CVGDE reached 22.4 %, and the aeration energy consumption was decreased to 5.48 Wh kg−1, which was 1000 times less than the energy consumption required for H2O2 electrosynthesis. The experiments and theoretical calculations showed that the dynamic equilibrium state of TPI was achieved by the influence of both the electric field and air flow in the catalyst layer, which leading to a substantial increase in oxygen mass transfer and H2O2 yield. Finally, CVGDE was utilized in the electro-Fenton process for the degradation of organic contaminants. This study will contribute to the understanding of the oxygen mass transfer process in GDE.