(321e) A Facile Route for the Synthesis of Nickel Nanoneedle

Down to nanoscale, properties of the material depend strongly on both the size and the morphology of the nanoparticles. Nickel nanoparticles find their applications in the areas that demand high specific surface area like catalysis, media for data recording, etc. In this work we propose a novel protocol for synthesis of nickel nanoneedles without the use of organic solvent at moderate temperature of 60 °C. Our method utilizes ability of hydrazine hydrate (HH) to simultaneously act as a reducing agent as well as a chelating agent. This enables us to eliminate the use of bulky organic molecules like surfactants or polymers that are commonly used as morphology modifiers in synthesis of anisotropic nanoparticles. This also implies that our protocol has potential for scale up as reuse and separation issues of the reagents are readily taken care of. These nanoneedles were synthesized by using Ni- acetate as metal precursor. High Resolution Transmission Electron Microscopy (HRTEM), High Resolution Scanning Electron Microscopy (HRSEM), Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) confirm material of the nanoparticles as nickel. Length of these nanoneedle ranges between 50 – 400 nm while diameter ranges between 8 – 14 nm. Effect of temperature (60 – 80 °C), Precursor concentration (35 – 105 mM), molar ratio of HH to precursor (2 – 10) and aging time (24 – 48 h) were investigated for understanding mechanism of formation of these nanoneedles. We have observed that concentration and temperature does not have significant effect on the size and shape of nanoneedles. Aging time however causes the increase in size of nanoparticles. Presence of amino group in HH seems to acts as shape inducing agent. A possible mechanism is consolidation of spherical particles to produce needle shaped particles. The exact mechanism is still under the investigation.