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In recent years, metal-organic framework derivatives have been regarded as materials with great potential for water treatment applications. In this study, we employed a polyvinylpyrrolidone (PVP)-assisted copper-cobalt bimetallic zeolitic imidazole framework (ZIF) as a template to rationally design nanosheet-like mixed metal oxide embedded nitrogen-doped carbon (CuCoO-PC). CuCoO-PC exhibited excellent degradation potential towards metronidazole (MNZ) and achieved almost complete degradation within 7 min through the activation of peroxymonosulfate (PMS). Importantly, the introduction of copper into CuCoO-PC established strong interactions between copper and cobalt, accelerating the activation performance of PMS. Furthermore, PVP, rich in nitrogen atoms, formed strong coordination interactions with ZIF precursors, which effectively protected the morphological stability of ZIF at high temperature, preventing collapse and aggregation. Meanwhile, the formation of nitrogen-doped carbon networks provides a pathway for the generation of non-radical. The study found that CuCoO-PC continuously activated PMS, generating various reactive oxygen species (ROS), among which SO 4 •- and 1O 2 played decisive roles. By calculating the HOMO, LUMO, and Fukui functions, we identified the reactive sites of MNZ and proposed possible degradation pathways. CuCoO-PC demonstrated excellent catalytic performance, reduced toxicity of intermediate products, and good reusability, all of which highlight its enormous potential in practical applications. [Display omitted] • CuCoO-PC composites are prepared using PVP to enrich the nitrogen content. • CuCoO-PC/PMS system exhibits prominent catalytic performance for MNZ removal. • SO 4 •- and 1O 2 was the main active substance involved in the MNZ degradation. • CuCoO-PC was stable and effective in multiple cycles of MNZ degradation efficiency. • The most reactive site on MNZ molecule was predicted by DFT calculation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A composite PMS activator of S-doped g-C 3 N 4 /NiCo 2 O 4 was obtained. • S doping widens the difference in the work functions of CNS and NCO. • Enhanced BIEF promotes the directional transfer of electrons from CNS to NCO. • 1O 2 was formed mainly through SO 4 •−, •OH and •O 2 − conversion. Transition metal oxide-mediated heterogeneous peroxymonosulfate (PMS) activation on organic pollutant degradation has attracted much attention, where continuous redox cycling between high and low valence metal ions is the key step as it relates to the radical generation. Herein, a composite PMS activator of S-doped g-C 3 N 4 /NiCo 2 O 4 (CNS_NCO) was constructed and exhibited excellent tetracycline (TC) degradation performance with 96.9% removal efficiency within 30 min. Experimental and theoretical calculations indicated that S doping not only widened the difference in the work function of CNS and NCO, but also enhanced the built-in electric field intensity of CNS_NCO heterojunctions, resulting in more electron transfer from CNS to NCO in a directional manner and accelerating the Co(III)/Co(II) and Ni(III)/Ni(II) redox cycle to form more reactive oxygen species (ROS). It was demonstrated that 1O 2 (main ROS) was formed mainly through SO 4 •−, •OH and •O 2 − (minor ROS) conversion. Meanwhile, high-valent cobalt-oxo (CoIV = O) species also played an important role in TC degradation. [ABSTRACT FROM AUTHOR]