2D metal-organic framework derived hollow Co/NC carbon sheets for peroxymonosulfate activation

2D metal-organic frameworks (MOFs) derivatives are a promising kind of heterogeneous catalysts to activate peroxymonosulfate (PMS) but suffer from severe structural collapse during the pyrolysis process. In this work, hollow Co/NC sheets (HCNSs-9) were prepared by pyrolysis of polydopamine (PDA) coated leaf-like Zn/Co zeolite imidazole framework (ZIFs-L@PDA). The bisphenol A (BPA) degradation performance of HCNSs-9 and two samples (ZIFs-L and ZIFs NP@PDA derived carbon) was evaluated and compared. The nitrogen isothermal adsorption and TEM characterization indicated the introduction of PDA can effectively protect the ZIFs-L morphology from collapsing at high temperature and form hollow hierarchical porous structure. When the resultant HCNSs-9 activated PMS to degrade BPA, significantly enhanced degradation performance was achieved. The reaction rate constant (k) is 0.341 min(-1), which is 2.3 and 6.1 times higher than that of ZIFs-L derived carbon (ZLC-9) and ZIFs NP@PDA derived carbon (ZNPC-9). Radical quenching experiments and electron paramagnetic resonance (EPR) tests confirmed the sulfate radicals (SO4 center dot-) are the dominant reactive oxygen species for BPA degradation. The residual PMS and generated SO4 center dot- in the heterogeneous systems were quantified. Besides, the conversion rate of PMS to SO4 center dot- was calculated, and the most suitable catalyst was determined. This work provides an effective and convenient method to synthesize hollow Co/NC sheets with enhanced performance for pollutant degradation.