Mechanochemical Preparation of Cobalt Nanoparticles through a Novel Intramolecular Reaction in Cobalt(II) Complexes

Abstract

A novel solid state reaction involving a series of cobalt(II) hydrazine‐azides has been used to prepare metallic cobalt nanoparticles. The reactions of [Co(N2H4)(N3)2], [Co(N2H4)2(N3)2], and [Co(N2H4)(N3)Cl]·H2O via NaOH, KOH as reactants were carried out in the solid state. These complexes undergo an intramolecular two‐electron oxidation‐reduction reaction at room temperature, producing metallic cobalt nanoparticles (Co1–Co6). The aforementioned complexes contain cobalt(II) that is an oxidizing agent and also hydrazine ligand as a reducing agent. Other products produced include sodium azide and ammonia gas. The cobalt metal nanoparticles were characterized using X‐ray powder diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The synthesized cobalt nanoparticles have similar morphologies; however, their particle size distributions are different.