Scalable synthesis of rose-like Co/N-doped porous rose-like structure for sustainable Rhodamine B degradation via peroxymonosulfate-driven advanced oxidation

This study developed a scalable synthesized rosette-like Co@NC-900 catalyst for the efficient degradation of Rhodamine B (RhB) via peroxymonosulfate (PMS) activation. The cobalt-organic precursor (Co-NDNP) was synthesized through a ligand-directed self-assembly strategy, followed by pyrolysis at 900℃, yielding the hierarchically porous Co@NC-900 catalyst. Comprehensive characterization revealed that this catalyst possesses a high specific surface area (659.76 m 2 /g), an abundance of mesopores, and numerous Co nanoparticles active sites, which collectively facilitate the uniform dispersion of Co nanoparticles and effectively mitigate metal leaching. During catalytic evaluation, the Co@NC-900/PMS system achieved > 90 % RhB degradation within 10 min, exhibiting a remarkably high apparent rate constant ( k obs ) of 0.0571 min −1 . Radical quenching experiments and electron paramagnetic resonance (EPR) analysis confirmed that singlet oxygen ( 1 O 2 ) served as the dominant reactive species, primarily generated via the Co 2+ /Co 3+ redox cycling kinetics on the Co nanoparticles. The system demonstrated exceptional degradation efficiency across a wide pH range (3−11), alongside robust tolerance to coexisting anions and humic acid. Degradation pathway analysis using high performance liquid chromatography-mass spectrometry (HPLC-MS) and three-dimensional excitation emission matrix fluorescence spectroscopy (3D EEM) spectroscopy elucidated the sequential breakdown of RhB through N-demethylation, ring cleavage, and mineralization. Furthermore, Ecological structure activity relationships (ECOSAR) modeling confirmed a significant reduction in the ecotoxicity of the final products. This research offers a valuable framework for designing stable and highly efficient catalysts for PMS activation.