Nickel flower-like nanostructures composed of nanoplates: one-pot synthesis, stepwise growth mechanism and enhanced ferromagnetic properties

Abstract

Nickel flower-like nanostructures composed of intercrossed nanoplates have been fabricated through a one-pot polyol reduction process without any surfactant or external magnetic field, where free Ni²⁺ ions slowly released from a solid intermediate phase are reduced by 1,2-propanediol under basic conditions. The morphology and size of the products can be kinetically tailored by properly tuning the synthetic parameters, including the concentrations of NiCl₂ and NaOH. A small amount of water in the 1,2-propanediol solution is inevitable for the growth of such flowery nanostructures. A stepwise growth mechanism is rationally proposed including the initial formation of nanospheres aggregated from nuclei and the subsequent site-specific oriented growth of nanoplates with basal planes of {111} facets at the quasi-equilibrium growth state. Such a flower-like nickel nanostructure shows a great enhancement of the ferromagnetic properties ascribed to the highly anisotropic shape of plate-like subunits. This work provides a facile strategy to fabricate stable nickel 3D nanostructures composed of nanoplates without losing their intrinsic 2D characteristics.