V2O5·3H2O/N-doped graphite felt cathode efficiently produced H2O2 and ·OH in the electro-Fenton system for enhanced antibiotics degradation

Enhancing H2O2 production and promoting the conversion of H2O2 to ·OH are two major problems that needed to be solved in electro-Fenton process. Herein, the V2O5·3H2O/N-doped graphite felt (V2O5·3 H2O/N-GF) cathode was developed to construct electro-Fenton system for antibiotics degradation. Benefiting from that the N-GF which possessed a large number of 2e-ORR active sites for H2O2 production, and the V2O5·3H2O particles could efficiently activate H2O2 to produce ·OH, the V2O5·3 H2O/N1-GF cathode exhibited outstanding catalytic activity. Besides, the V2O5·3 H2O/N1-GF cathode exhibited only 30 mV overpotential difference between the optimal oxygen reduction potential (OP ORR) and the optimal vanadium reduction potential (OP VRR), thereby facilitating ·OH generation. The V2O5·3 H2O/N1-GF cathode displayed desired degradation performance in a wide pH range (2.1–7.2), with TC removal of 93.8% within 60 min at pH of 3.3, and total organic carbon (TOC) removal of 62.8%. DFT calculations revealed that V2O5·3H2O were more readily to adsorb H2O2 than V2O5, which was conducive to improving H2O2 utilization and conversion. Four possible degradation pathways for TC were proposed and toxicity analysis of the intermediates were determined. The V2O5·3H2O/N1-GF could also decompose various antibiotics effectively in the system, and it exhibited great stability. This work can provide reference for designing efficient V-based cathode for electro-Fenton system.