Supramolecular cucurbit[7]uril-engineered Co/Ca bimetallic nitrogen-doped carbon: Structural regulation for sustainable advanced oxidation.

Sulfate radical-based advanced oxidation processes (SR-AOPs) for antibiotic degradation are often hindered by the aggregation and toxic leaching of cobalt catalysts. Herein, we engineered a supramolecular cucurbit[7]uril (CB[7])-derived Co/Ca bimetallic nitrogen-doped carbon (CoCa/CN) catalyst. During pyrolysis, the earth-abundant calcium acted as an in-situ porogen and structural pillar, yielding a hierarchical porous C/N framework that spatially confined Co nanoparticles and prevented sintering. The optimized CoCa/CN exhibited exceptional peroxymonosulfate (PMS) activation, achieving outstanding degradation efficiency across various antibiotics. Tetracycline hydrochloride (TCH) was selected for detailed investigation, achieving 97.3% removal within 30 min. Mechanistic studies revealed a highly efficient singlet oxygen (1O2)-dominated non-radical pathway, alongside minor radical contributions. Density functional theory (DFT) calculations demonstrated that Ca incorporation optimized the electronic environment, significantly enhancing PMS adsorption and accelerating interfacial electron transfer to stabilize the Co0/Co2+/Co3+ redox cycle. Furthermore, the system demonstrated robust pH adaptability, excellent anti-interference in complex water matrices, and successfully eliminated TCH developmental toxicity in zebrafish embryos. This study offers a sustainable paradigm for designing highly stable, eco-friendly bimetallic catalysts for environmental remediation.