In-situ preparation of hollow cellulose nanocrystals/zeolitic imidazolate framework hybrid microspheres derived from Pickering emulsion

In situ interfacial growth of nanoparticles induced by a Pickering emulsion is recognized as a practical method for the fabrication of hollow composites. Herein, hybrid hollow microspheres were prepared using cellulose nanocrystals (CNCs) emulsified water-dodecane system as a template. The hybrid microspheres were composed of zeolitic imidazolate framework-8 (ZIF-8) shells and CNCs surface-layers. ZIF-8 crystals formed and grew at the oil-water interface with a low ligand/metal ion molar ratio. The composite microspheres owned rich porous structure with a high surface area of 1240 m² g^-1 and performed obvious hydrophilicity owing to the role of CNCs layers. The two characters offered CNCs/ZIF-8 composite materials with very prominent adsorption capacity towards dyes (1060.2 mg g^-1 for malachite green). Carbonization of CNCs/ZIF-8 composite materials afford ZIF-8 based materials more effective removal of methylene blue from water under sunlight, owing to the photocatalytic role of ZnO remained in carbonized product. This research paves the way to realize a variety of hollow CNCs/ZIFs hybrid materials for different application purposes.