Amphiphilic triblock copolymer-assisted synthesis of hierarchical NiCo nanoflowers by homogeneous nucleation in liquid polyols

Rose-like NiCo nanotlowers were synthesized by homogeneous, one-pot polypi reduction of Ni and Co-acetates in presence of an amphiphilic triblock copolymer and KOH. 1,2-propanediol was used as solvent-aim-reducing agent as no external reducing agent was found to be necessary in this process. Detailed x-ray diffraction and morphological characterizations confirmed formation of fcc hierarchical NiCo nanollowers containing 20 nanosheet-like subunits (thickness of about 30 nm) with an average diameter of similar to 700 nm. Amphiphilic polymer played a pivotal role in the growth of nanorose as it favored a preferential growth of nanocrystals along a particular crystal plane as was observed in transmission electron microscopy. Effects of other parameters like use of hydrophilic polymer, surfactants, ratio of initial metal concentrations, choice of polyol media and concentration of KOH on the morphology of nanollowers were also investigated. Room temperature magnetic studies revealed higher saturation magnetization and low coercivity (108.6 emu/g and 784 Oe) of nanorose. Based on LaMer model, a kinetically-controlled growth mechanism for the formation of NiCo nanorose is also proposed. (C) 2014 Elsevier B.V. All rights reserved.