Rational design of magnetic MOFs-COFs hybrid nanozyme for the colorimetric detection of phenol

Phenol is highly toxic and can cause damage to humans and the ecosystem even at low concentrations. Therefore, developing a rapid, sensitive and easy operated detection strategy still faces challenge. In this work, the covalent organic frameworks (COFs)-reinforced peroxidase-mimicking hybrid nanozyme was rationally designed by assembly COFs on magnetic Fe3O4 @ZIF-8 nanozyme. The Fe3O4 @ZIF-8 @COF hybrid nanozyme exhibited significant improved catalytic activity and can be developed as a rapid and sensitive phenol colorimetric sensor with ease operation. The core-shell structure and the crystallinity of the as-prepared hybrid nanozyme were characterized in detail by various analytical methods SEM, TEM, FT-IR, XRD and elemental mapping. The catalytic activity of Fe3O4 @ZIF-8 @COF mimic enzyme was investigated in the presence of H2O2 using 4-aminoantipyrine (4-AAP) as the substrate. The developed Fe3O4 @ZIF-8 @COF hybrid nanozyme was applied to construct colorimetric sensor for phenol detection and the result presented high selectivity, excellent stability and good reusability with a wide linear range (6–350 μM), low detection limit (2 μM) and an advantageous response time (5 min). The designed catalyst makes the enhancement of peroxidase-like activity, which can be attributed to the unique core-shell structure with the inner catalytic site and the outer protection and enrichment COF shell. Therefore, this proposed colorimetric sensor with robust, stable and easy-recycled properties displayed excellent practical significance for the fast and sensitive detection of phenol in water environment.