Boosting hydrogen peroxide accumulation by a novel air-breathing gas diffusion electrode in electro-Fenton system

Electro-Fenton (EF) is a promising electrochemical technology in degrading recalcitrant organic pollutants. However, the technology faces problems of high energy consumption, low cathodic oxygen transfer rate and low H2O2 production efficiency. Therefore, a novel air-breathing gas diffusion electrode (GDE) with multiform hydrophobic layers was prepared by a facile method. The novel GDE allows the air to diffuse to the triphase interface spontaneously, eliminating the cost of aeration. Also, the multiform hydrophobic layers can greatly improve the oxygen transfer rate and expand the triphase interfaces in the GDE, resulting in a high H2O2 accumulation of 44.30 mg L−1 cm−2 h−1 without aeration, which was 18 times higher than that of the virgin cathode. A 100% degradation efficiency of sulfadiazine (SDZ) was achieved with the fabricated GDE in 10 min in EF system. Moreover, theoretical calculations were performed for accurately elucidating the SDZ degradation mechanism and pathway. [Display omitted] •Air can diffuse into the electrode spontaneously with high diffusion coefficient.•Multiform hydrophobic layers in the electrode boosted H2O2 accumulation.•The SDZ degradation process was elucidated using theoretical calculations.