Ultrathin CoO@NC nanosheets derived from NaBH4-treated ZIF-67 for ofloxacin degradation

An ultrathin CoO@NC nanosheet is prepared with NaBH4-treated ZIF-67 and can degrade ofloxacin rapidly and effectively as an AOP catalyst. • After treated by NaBH4, ZIF-67 is partially delaminated and curled. • The derived CoO@NC exhibits an ultrathin carbon nanosheet loaded with highly dispersed CoO NPs. • The CoO@NC can decompose ofloxacin via both radical and non-radical pathways. • A high ofloxacin removal efficiency (96.8 %) is achieved by P-CoO@NC after reacting for 10 min. • Four ofloxacin degradation pathways are proposed. Modulating the morphology of precursor can effectively adjust the property of derived composite. Herein, after post-treated by NaBH 4 , a layered ZIF-67 precursor was endowed with high porosities, partially delaminated and curled layers. With this material as precursor, the pyrolysis composite, P-CoO@NC, exhibits a morphology of ultrathin N-doped carbon (NC) nanosheets coupled with highly dispersed CoO nanoparticles. This composite can active peroxymonosulfate (PMS) and degrade ofloxacin (OFL) with an efficiency of 96.8 % (10 min). After recycling for five times, the degradation efficiency can still reach 82.5 %, which demonstrates its catalytic activity and stability as an advance oxidation process (AOP) catalyst. As confirmed by related experiments, both radical (SO 4 — and O 2 — ) and non-radical ( 1 O 2 ) pathways take part in OFL degradation in P-CoO@NC system. Overall, this work demonstrates a specific role of NaBH 4 in modulating MOF precursor and further the property of derived composite.