A facile solution to mature cathode modified by hydrophobic dimethyl silicon oil (DMS) layer for electro-Fenton processes: Water proof and enhanced oxygen transport

Abstract

Water flooding in the microporous cathode is poisonous but inevitable for oxygen reduction reaction (ORR) in electro-Fenton (EF) processes. To meet this challenge, a facile modification was reported to stabilize performance of cathode through the infiltration process, which selecting superior CB-PTFE electrode as backbone and dimethyl silicon oil (DMS) as maturation layer. Characterized by FE-SEM, EDS, BET, XRD, the matured cathode was proved to be wrapped uniformly by DMS. Electrochemical performances of cathodes were evaluated by CA, CV, EIS and CP measurements in oxygen “starvation” condition. These results proved that the maturation layer improved the electrocatalysis on 2e− ORR, the service lifetime from 1.68 h to 18.34 h, the working range of current density from 70 to 110 A m−2 and reduced the oxygen diffusion resistance from 74.23 to 8.07 Ω. Besides, H2O2 generation and oxygen utilization of 2%DMS cathode respectively reached 126.7 mg L−1 and 83.49% in 60 min, which were rarely influenced by pH and aeration rate even after water flooding process. 2%DMS layer served as the accelerated oxygen transport channel can explain the enhanced oxygen transport. The simulated contaminated solution containing a fungicide-flutriafol (FTF) was obtained 100% removal in about 40 min and 48.88% TOC removal in 2 h. The lifetime tests revealed much more stable decay of FTF under the broader operational condition.