ZnO-Co3O4/N-C Cage Derived from the Hollow Zn/Co ZIF for Enhanced Degradation of Bisphenol A with Persulfate

The zeolitic imidazolate framework (ZIF)-67 microcrystal was employed as a precursor to synthesize the hollow ZIF-8/ZIF-67 composite via the epitaxial growth of ZIF-8 on ZIF-67, in situ self-sacrifice, and excavation of ZIF-67. The hollow ZIF-8/ZIF-67 composite was successfully transformed to the ZnO-Co3O4/N-C cage by thermal treatment, which was further used as the catalyst for the oxidative degradation of bisphenol A (BPA) in the presence of potassium persulfate (PS). In comparison with the Co3O4/N-C and Co3O4 obtained from pure ZIF-67 and cobalt nitrate, the ZnO-Co3O4/N-C cage demonstrated a more than four fold-higher activity and robust reusability. Based on structural analysis, the enhanced catalytic performance could be ascribed to the small, highly dispersed cobalt oxide particles, the hollow structure that facilitated the transportation of the molecules, and the synergistic effect between cobalt oxide and nitrogen-doped carbon in the composite. Besides, the effect of dosage of PS, BPA, and the co-existing components such as chloride ion, methanol, and t-butyl alcohol was carefully investigated to propose the possible mechanism. This study would give new insights into the design of functional composite materials from metal organic frameworks and the development of their application in environmental pollution disposal.