Hierachical Ni@Fe2O3superparticles through epitaxial growth of γ-Fe2O3nanorods on: In situ formed Ni nanoplates

One endeavour of nanochemistry is the bottom-up synthesis of functional mesoscale structures from basic building blocks. We report a one-pot wet chemical synthesis of Niatγ-Fe2O3superparticles containing Ni cores densely covered with highly oriented γ-Fe2O3(maghemite) nanorods (NRs) by controlled reduction/decomposition of nickel acetate (Ni(ac)2) and Fe(CO)5. Automated diffraction tomography (ADT) of the Ni-Fe2O3interface in combination with Mössbauer spectroscopy showed that selective and oriented growth of the γ-Fe2O3nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3interface. The common orientation of the maghemite nanorods on the Ni core of the superparticles leads to a greatly enhanced magnetization. After functionalization with a catechol-functional polyethylene glycol (C-PEG) ligand the Niatγ-Fe2O3superparticles were dispersible in water.