Surging efficient PMS activation through a COF-MOF dual immobilized catalytic platform: Synergy of enhanced electron transfer and adsorption-PMS activation

In heterogeneous catalytic systems used for peroxymonosulfate (PMS) catalysis, the effectiveness of the catalyst and the leaching rate of metal ions have gained considerable attention. Taking inspiration from the advantages of combining covalent organic frameworks (COF) and metal–organic frameworks (MOF) to facilitate charge transfer and metal immobilization, this study proposes an alternative method through immobilizing the catalysts with MOF and COF coating. The synthesis of Co-Fe3O4@UiO-66@TpBD was carried out with a pre-synthesizing method, followed by COF coating through a Schiff-based reaction. The introduction of MOF has largely limited the metal leaching from 7.85 mg/L to 1.03 mg/L, and the subsequent introduction of COF has enhanced electron transfer and adsorption of PMS, as well as a further reduction in the metal leaching from 1.03 mg/L to 0.50 mg/L. Impressively, the dual immobilization strategy has guaranteed a more stable utility and the materials showed comparable performances even after 5 cycles. Moreover, singlet oxygen (1O2) is the dominant reactive oxygen species responsible for the degradation through electrophilic substitution of Acetaminophen (APAP).