A core-shell structure MOF-derived carbon material FeMo@NPC-700 cathode with transition metal nitride for rapid tetracycline degradation in an electro-Fenton system: The role of Fe3N and the synergistic effect of Mo

Calcination temperature affects the formation of metal species. By calcining nitrogen-doped Fe/Mo bimetallic MOF at a higher temperature (700 °C), a core-shell structure MOF-derived carbon material (FeMo@NPC-700) containing transition metal nitride (TMN) was successfully prepared and used as a cathode for the degradation of tetracycline (TC) in the electro-Fenton system. Due to the high catalytic activity of TMN and the synergistic catalytic effect of Mo, the FeMo@NPC-700 cathode achieved 98.9% removal of TC within 30 min and 51% removal of total organic carbon (TOC) within 60 min. It was verified that Fe 3 N played an important role in the degradation of TC, contributing 68% to the degradation. In addition, quantitative analysis of the reactive oxygen species (ROSs) in the system showed that ·OH was the main ROS dominating the degradation of tetracycline. Finally, four possible pathways of TC degradation were proposed based on HPLC-MS analysis, and the toxicity of the intermediates was analyzed by ecological active-structure relationship. This study provides a reference for the preparation of MOF-derived carbon materials containing TMN.