High-Yield Solvothermal Synthesis of Magnetic Peapod Nanocomposites via the Capture of Preformed Nanoparticles in Scrolled Nanosheets

A versatile method has been developed for the fabrication of magnetic peapod nanocomposites with preformed nanoparticles (NPs). With use of a solvothermal treatment, NPs combined with acid-exchanged hexaniobate crystallites readily produce nanopeapods (NPPs). This approach is effectively demonstrated on a series of ferrite NPs (<= 14 nm) where Fe3O4@hexaniobate NPPs are rapidly (similar to 6 h) generated in high yield. When NP samples with different sizes are reacted, clear evidence for size selectivity is seen. Magnetic dipolar interactions between ferrite NPs within the Fe3O4@hexaniobate samples lead to significant rise in coercivity, increasing almost fourfold relative to free particles. Other magnetic ferrites NPPs, MFe2O4@hexaniobate (M = Mn, Co, Ni), can also be prepared. This synthetic approach to nanopeapods is quite versatile and should be readily extendable to other, nonferrite NPs or NP combinations so that cooperative properties can be exploited while the integrity of the NP assemblies is maintained.