Polymer tethering strategy modified ZIF67 derived cobalt-confined nanocage for norfloxacin degradation: Tailored reactive sites and beneficial local microenvironment

[Display omitted] •Cobalt-incorporated polymer tethering strategy modified ZIF67 was exploited to regulate the distribution of active species.•More polar-nitrogen-species trigger the rapid surface enrichment of contaminants around the active sites.•The higher unpaired-electron-oxygen onto cobalt is used as an acidic intermediate to enhance the catalytic reaction.•The unpaired electron oxygen induce the impurity cleavage of O-O bond, promoting the generation of 1O2.•The mineralized efficiency can be maintained when involving two contaminants in one system. The refined state of reactive sites and their local microenvironment largely determined the reaction performance of catalyst. Herein, we constructed hollow cobalt-confined carbon nanocage (Co-NC@Co/C-x) with rich surface pyridinic N and more exposed tailored Co sites through cobalt-incorporated polymer tethering strategy modified ZIF67 and later thermal depolymerization. Such features facilitate rapid surface enrichment of contaminants, accelerated electron transfer and enhance the availability of unpaired electron oxygen of metallic cobalt, demonstrating exceptional efficiency in Norfloxacin degradation (NFX, 97.7 % within 20 min, kobs = 0.528 min−1) with a significantly lower activation energy of 6.39 KJ mol−1. Mechanistic investigations prove the promotive interplay of peroxymonosulfate with reactive sites and elucidate the dominant role of non-free radicals 1O2 for NFX degradation. The theoretical calculation showcases that unpaired-electron surface oxygen of metallic cobalt induces the impurity cleavage of the O-O bond, triggering the promotive generation of 1O2. Co-NC@Co/C-6 samples exhibit robust NFX degradation across different aqueous matrices, demonstrating cyclic stability and universal degradation performance against various pollutants, and flowing degradation experiments and immobilized recyclable monolith fiber-like bobbles experiments further underline the green recovery and practical potential in wastewater treatment.