“Floating” cathode for efficient H2O2 electrogeneration applied to degradation of ibuprofen as a model pollutant

The performance of the Electro-Fenton (EF) process for contaminant degradation depends on the rate of H 2 O 2 production at the cathode via 2-electron dissolved O 2 reduction. However, the low solubility of O 2 (≈1 × 10 −3  mol dm −3 ) limits H 2 O 2 production. Herein, a novel and practical strategy that enables the synergistic utilization of O 2 from the bulk electrolyte and ambient air for efficient H 2 O 2 production is proposed. Compared with a conventional “submerged” cathode, the H 2 O 2 concentration obtained using the “floating” cathode is 4.3 and 1.5 times higher using porous graphite felt (GF) and reticulated vitreous carbon (RVC) foam electrodes, respectively. This surprising enhancement results from the formation of a three-phase interface inside the porous cathode, where the O 2 from ambient air is also utilized for H 2 O 2 production. The contribution of O 2 from ambient air varies depending on the cathode material and is calculated to be 76.7% for the GF cathode and 35.6% for the RVC foam cathode. The effects of pH, current, and mixing on H 2 O 2 production are evaluated. Finally, the EF process enhanced by the “floating” cathode degraded 78.3% of the anti-inflammatory drug ibuprofen after 120 min compared to only 25.4% using a conventional “submerged” electrode, without any increase in the cost.