Hierachical Ni@Fe2O3 superparticles through epitaxial growth of gamma-Fe2O3 nanorods on in situ formed Ni nanoplates: 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 Ni@gamma-Fe2O3 superparticles containing Ni cores densely covered with highly oriented gamma-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-Fe2O3 interface in combination with Mossbauer spectroscopy showed that selective and oriented growth of the gamma-Fe2O3 nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95 alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3 interface. 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 Ni@gamma-Fe2O3 superparticles were dispersible in water.