Free-Floating 2D Nanosheets with a Superlattice Assembled from Fe3O4 Nanoparticles for Peroxidase-Mimicking Activity.

The organization of nanoparticles (NPs) with controlled chemical composition and size distribution into well-defined sheets will find many practical applications, but the chemistry remains problematic. Therefore, we report a facile method to assemble NPs to free-floating two-dimensional (2D) nanosheets with a superlattice and thicknesses reaching 22.8 nm. The ligand oleic acid is critical in the formation of nanosheets. As assembled, these free-floating 2D nanosheets remain intact in both polar and nonpolar solvents, e.g., deionized water, ethanol, N,N-dimethylformamide, dimethyl sulfoxide, toluene, hexane, and chloroform, without any disassembly. Compared to Fe3O4 NP building blocks, these 2D nanosheets show more favorable catalytic properties and enhanced catalytic reactivity, which can be exploited to mimic natural enzymes. Our work is expected to open up a new avenue for synthesizing free-floating 2D supersheets by NP assembly, leading to a new generation of materials with enriched functions and broader applications.