A Natural Oxygen-Harvesting Electrode Enables Aeration-Free Electrochemical Advanced Oxidation for In Situ Water...

Electro-Fenton treatment through the two-electron oxygen reduction reaction (2e^- ORR) offers an effective approach for degrading persistent organic pollutants (POPs) in water; however, aeration is always required to overcome the low solubility of oxygen in water, ensuring adequate oxygen availability for the 2e^- ORR to generate H₂O₂ and facilitate its transport for activation into hydroxyl radicals. The aeration energy consumption can reach tens of times higher than the energy required for the electrochemical reactions themselves. To address this, we developed an aeration-free dual-cathode system featuring a natural oxygen-harvesting electrode (NOHE). The NOHE's superhydrophobic and microporous structure effectively captures and utilizes anode-generated oxygen for H₂O₂ synthesis (957.1 mg g_cat ^-1) without external aeration. By decoupling H₂O₂ generation and activation into separate cathodes, the system optimizes both processes independently, achieving superior efficiency. This design demonstrated rapid removal of bisphenol AF (BPAF) in saline environments, achieving 98% mineralization and exhibiting excellent operational stability over 90 h continuous use. By eliminating energy-intensive aeration, our approach may open the avenue for a scalable, sustainable solution for in situ water remediation, with broad applicability in diverse aquatic environments.