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In this work, nitrogen-doped cathodes for high H 2 O 2 production and sulfathiazole (STZ) degradation in electro-Fenton (EF) systems were prepared by the carbonization of three carbon/nitrogen-enriched precursors. Among the cathodes elaborated from different precursors, the one using 1h-1,2,4-triazole-3,5-diamine as the precursor showed the best oxygen reduction reaction (ORR) ability with the normalized H 2 O 2 accumulation of 9.49 ± 0.03 mg L -1  h -1  cm -2 compared to the other two N-containing cathodes. The enhanced H 2 O 2 accumulation was attributed to the high electroactive surface area and pyrrolic N (60.45%) content. Regarding reactive oxygen species in the absence of Fe 2+ , aside from the H 2 O 2 , O 2 - and 1 O 2 were identified using spectroscopic techniques and chemical probes. As a result, a degradation and mineralization efficiency of 98.25 ± 0.14% and 70.57 ± 0.27% of STZ were attained in the 180-min treatment, mainly coming from the homogeneous OH from classical Fenton, anodic OH on BDD anode and direct/indirect oxidation of O 2 - and 1 O 2 . In addition, the plausible degradation pathway of STZ was proposed based on the density functional theory (DFT) combined with experimental data derived by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The frontier orbital theory and Fukui function theoretically suggested the vulnerable sites of STZ for different active species including OH, O 2 - and 1 O 2 . This study provides a new strategy for improving the ORR process and analyzing the generation and conversion of reactive oxygen species in the EF process., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)