Bio-inspired Cu₂O cathode for O₂ capturing and oxidation boosting in electro-Fenton for sulfathiazole decay

A hydrophobic Cu₂O cathode (Cu_xO-L) was designed to solve the challenge of low oxidation ability in electro-Fenton (EF) for treating emerging pollutants. This fabrication process involved forming Cu(OH)₂ nanorods by oxidizing copper foam (Cu-F) with (NH₄)₂S₂O₈, followed by coating them with glucose via hydrothermal treatment. Finally, a self-assembled monolayer of 1-octadecanethiol was introduced to create a low-surface-energy, functionalized Cu_xO-L cathode. Results exhibited an approximately 7.9-fold increase in hydroxyl radical (·OH) generation compared to the initial Cu-F. This enhancement was attributed to two key factors: (Ⅰ) the superior O₂-capturing ability of Cu_xO-L cathode, which led to high H₂O₂ production due to a 2 nm thick hydrophobic gas layer facilitated O₂-capturing; (Ⅱ) a relative high concentration of Cu⁺ at the Cu_xO-L cathode promoted the activation of H₂O₂ into·OH. In addition, the performance of EF with the Cu_xO-L cathode using sulfathiazole (STZ) as a model pollutant was evaluated. This study offers valuable insights into the design of O₂-capturing cathodes in EF processes, particularly for treating emerging organic pollutants.