Nitrogen vacancy-induced d-band center upshift in Co4N-600 nanozyme breaks the oxygen wall and facilitates CoIV=O formation for emerging contaminants degradation

High‑valent cobalt-oxo species (CoIV=O) have been demonstrated to exhibit efficient degradation capability toward emerging contaminants (ECs). However, the 3d7 electronic configuration of Co(II) sites in Co‑based catalysts severely restricts their binding affinity to the terminal oxygen of peroxymonosulfate (PMS), which is unfavorable for the generation of CoIV=O. Herein, we report a nitrogen vacancy (Nv)‑rich cobalt nitride nanozyme Co4N-600. The introduction of Nv markedly reduces the d‑electron occupancy of Co, upshifts the d‑band center, and promotes the formation efficiency of CoIV=O. Remarkably, employing 150 mg L-1 peroxymonosulfate (PMS) as the oxidant, the Co4N-600 nanozyme achieves complete degradation of 10 mg L-1 imidacloprid within 10 min at an ultralow catalyst loading of 1 mg L-1, yielding an excellent modified kinetic rate constant of 300.6 min-1 M-1. These findings establish d-band center engineering as an effective strategy for boosting the catalytic performance of nanozymes by promoting the generation of high-valent metal-oxo (HVMO) species.