Nitrogen moieties -dominated Co–N-doped nanoparticle-modified cathodes in heterogeneous-electro-Fenton-like system for catalytic decontamination of EDTA-Ni(II)

Ethylenediaminetetraacetic acid (EDTA) could form stable complexes with toxic metals such as nickel due to its strong chelation. In this study, with the same doping level of Co and N, MoO 2 and ZIF-67 were used as precursors to prepare MoO 2 @Co/N and FeC@Co/N electrocatalysts for the modified graphite felt cathodes in heterogeneous-electro-Fenton-like reaction (HEFL) system. The X-ray diffraction and X-ray photoelectron spectroscopy results indicated that both of the catalysts are dominated with pyridinic N (2.42% and 2.82%) upon co-doping Co/N, and FeC@Co/N exhibited an obviously higher additional sp -hybridized nitrogen ( sp -N) peak. The co-doping of Co/N induced the lattice modifications to produce more lattice defects, where pyridinic N and sp -N, related with the active sites (C–N, Co-Nx), were formed at near-ring defects along sheet edges through the nitrogen replacement of C C groups. FeC@Co/N demonstrated superior oxygen reduction reaction catalytic activity in terms of Cyclic Voltammetry and Rotating Ring-disk Electrode, and exhibited the remarkably higher current density (30 mA) and lower onset potential (−0.208 V) in Linear Sweep Voltammetry analysis. In the FeC@Co/N/CF modified HEFL system, despite the generated H 2 O 2 concentrations (62.5 mg L −1 ) is not very high, the reducing reaction of ≡Fe(III)/Co(III)–OH could get the electron directly from the cathode, which would greatly reduce the consumption of H 2 O 2, high utilization efficiency of H 2 O 2 (η: 87.63%) could greatly improve the EDTA-Ni removal (97.5%) and TOC (92.6%). This work demonstrates the feasibility of utilizing FeC@Co/N/CF as a cathode for breaking metal-complex in HEFL process.