A Generic Method for Preparing Hollow Mesoporous Silica Catalytic Nanoreactors with Metal Oxide Nanoparticles inside Their Cavities

We report a facile and generic method for the synthesis of hollow mesoporous silica nanoreactors (HMSNs) with small-sized metal oxide nanoparticles (NPs) inside their cavities. They were made by deposition of silica onto metal-containing charge-driven polymer micelles and subsequent calcination. The micelles consist of 1)negatively charged supramolecular polyelectrolyte chains of bis-ligand-bound metal ions, and 2)water-soluble, neutral/positive diblock copolymers. Owing to the facile coordination between transition-metal ion and the employed bidentate ligand, a series of HMSNs with <2nm MxOy NPs inside cavities (M=Mn, Co, Ni, Cu, or Zn) were obtained by simply varying the metal ions inside the micelles. The developed method circumvents the pre- and post-synthesis of metal oxide NPs; after calcination, hollow mesoporous nanostructures containing small-sized metal oxide NPs inside their cavities are directly obtained. The CoxOy-functionalized HMSNs catalyze the degradation of various dyes with H2O2.