Regulating cobalt-nitrogen function centers via Cu incorporation enhances ciprofloxacin destruction through peroxymonosulfate activation

Metal-nitrogen (M-N) coupling has shown promise as a catalytic active component for various reactions. However, the regulation of heterogeneous catalytic materials with M-N coupling for peroxymonosulfate (PMS) activation to enhance the degradation efficiency and reusability of antibiotics remains a challenge. In this study, an efficient modulation of M-N coupling was achieved through the incorporation of Cu into Co4N to form a Cu-Co4N composite with sea urchin-like morphology assembled by numerous nano-needles using hydrothermal and nitriding processes. This modulation led to enhanced PMS activation for ciprofloxacin (CIP) degradation. The Cu-Co4N/PMS system demonstrated exceptional removal efficiency with a degradation rate of 95.85% within 30 min and can be reused for five time without obvious loss of its initial activity. Additionally, the catalyst displayed a high capacity for degrading various challenging organic pollutants, as well as remarkable stability, resistance to interferences, and adaptability to pH changes. The synergistic effect between Co and Cu facilitated multiple redox cycles, resulting in the generation of reactive oxidized species. The primary active species involved in the catalytic degradation process included 1O2, SO4•-, O2•-, •OH, and e−, with 1O2 and SO4•- playing the most significant roles. The degradation pathways and toxicity of the intermediates for CIP were unveiled. This study offers valuable insights into the regulation of M-N centers for degrading antibiotics through PMS activation.