Hierarchical Coating Nanoarchitectonics of Halloysite Nanotube with Polydopamine and ZIF-8 for Adsorption of Organic Contaminants

Coating nanoparticles with metal–organic frameworks (MOFs) can lead to core–shell hybrid particles with synergetic functionalities of the respective components. Previous efforts have been dedicated to achieving homogeneous and smooth MOF coatings with featureless morphologies. Herein, using halloysite nanotubes (HNTs) coated with polydopamine (PDA) to confine nucleation and growth of ZIF-8 on the surface, we prepared rod-like core–shell HNT@PDA@ZIF-8 particles. The ZIF-8 coating has a hierarchical morphology consisting of nanoaggregates of densely packed and fused ZIF-8 nanoparticles. This was achieved by simply controlling the concentration of the MOF precursors. These hybrid MOF particles combine the classical large microporosities with meso- and macroporosities derived from such hierarchical structures, while has enhanced mechanical stability. HNT@PDA@ZIF-8 exhibits appreciated adsorption capacity for several organic contaminants in aqueous system, especially for Rhodamine B.