Magnetic microsphere with hierarchical LDH/polydopamine shell encapsulated Fe3O4 core for carrying Ag nanocatalyst

An efficient and green carrier for noble metal nanocrystals is very important for nanocatalysis. During the past decade, various efforts have been focused on developing hierarchical nanostructures for carrying nanocrystals due to the unique surface characteristics. By combining the magnetic separation, high loading, and easy preparation advantages together, this work reports a simple method to fabricate Fe3O4@LDH/PDA core shell microspheres for carrying Ag nanoparticles. The tri-component Fe3O4@LDH/PDA nanostructure is featured with a magnetic Fe3O4 core and a layered double hydroxides (LDH) supported polydopamine (PDA) hierarchical shell. Through a tailored surface engineering process, a series of Fe3O4@LDH/PDA microspheres with tunable sizes, shell thicknesses, and surface function are constructed. Due to the highly active hierarchical surface, the Ag nanocrystals are easily to be immobilized on the Fe3O4@LDH/PDA to form flowerlike Fe3O4@LDH/PDA-Ag multifunctional nanocomposites. The Fe3O4@LDH/PDA-Ag shows high catalytic activity on reducing the 4-Nitrophenol and its catalytic ability can keep 91 % after 8 cycles. In consideration of the biocompatibility, hierarchical surface, and magnetic separation, this kind of materials is expected to be further applied in enzyme immobilization, anti-bacterial, drug delivery, and pollution separation.